Refactor Skylark Environment-s
Make Environment-s freezable: Introduce a class Mutability
as a revokable capability to mutate objects in an Environment.
For now, only Environment-s carry this capability.
Make sure that every Mutability is revoked in the same function that creates it,
so no Environment is left open for modification after being created and exported;
exceptions for tests, the shell and initialization contexts.
Unify Environment, SkylarkEnvironment and EvaluationContext into Environment.
Have a notion of Frame for the bindings + parent + mutability.
Replace the updateAndPropagate mechanism by a dynamicFrame.
Simplify ValidationEnvironment, that is now always deduced from the Environment.
--
MOS_MIGRATED_REVID=102363438
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BaseFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/BaseFunction.java
index 8d5f48f..d28d4d3 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BaseFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BaseFunction.java
@@ -407,35 +407,29 @@
* @param args a list of all positional arguments (as in *starArg)
* @param kwargs a map for key arguments (as in **kwArgs)
* @param ast the expression for this function's definition
- * @param parentEnv the lexical Environment for the function call
+ * @param env the Environment in the function is called
* @return the value resulting from evaluating the function with the given arguments
* @throws construction of EvalException-s containing source information.
*/
public Object call(List<Object> args,
@Nullable Map<String, Object> kwargs,
@Nullable FuncallExpression ast,
- @Nullable Environment parentEnv)
+ Environment env)
throws EvalException, InterruptedException {
- Environment env = getOrCreateChildEnvironment(parentEnv);
- env.addToStackTrace(new StackTraceElement(this, kwargs));
+ Preconditions.checkState(isConfigured(), "Function %s was not configured", getName());
+
+ // ast is null when called from Java (as there's no Skylark call site).
+ Location loc = ast == null ? Location.BUILTIN : ast.getLocation();
+
+ Object[] arguments = processArguments(args, kwargs, loc);
+ canonicalizeArguments(arguments, loc);
+
try {
- Preconditions.checkState(isConfigured(), "Function %s was not configured", getName());
-
- // ast is null when called from Java (as there's no Skylark call site).
- Location loc = ast == null ? location : ast.getLocation();
-
- Object[] arguments = processArguments(args, kwargs, loc);
- canonicalizeArguments(arguments, loc);
-
- try {
- return call(arguments, ast, env);
- } catch (EvalExceptionWithStackTrace ex) {
- throw updateStackTrace(ex, loc);
- } catch (EvalException | RuntimeException | InterruptedException ex) {
- throw updateStackTrace(new EvalExceptionWithStackTrace(ex, loc), loc);
- }
- } finally {
- env.removeStackTraceElement();
+ return call(arguments, ast, env);
+ } catch (EvalExceptionWithStackTrace ex) {
+ throw updateStackTrace(ex, loc);
+ } catch (EvalException | RuntimeException | InterruptedException ex) {
+ throw updateStackTrace(new EvalExceptionWithStackTrace(ex, loc), loc);
}
}
@@ -556,7 +550,7 @@
if (pos < howManyArgsToPrint - 1) {
builder.append(", ");
}
- }
+ }
builder.append(")");
return builder.toString();
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
index a7547de..aa9b151 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
@@ -122,9 +122,11 @@
@Override
@Nullable
public Object call(Object[] args,
- @Nullable FuncallExpression ast, @Nullable Environment env)
+ FuncallExpression ast, Environment env)
throws EvalException, InterruptedException {
- final Location loc = (ast == null) ? location : ast.getLocation();
+ Preconditions.checkNotNull(ast);
+ Preconditions.checkNotNull(env);
+ Location loc = ast.getLocation();
// Add extra arguments, if needed
if (extraArgs != null) {
@@ -150,6 +152,7 @@
long startTime = Profiler.nanoTimeMaybe();
// Last but not least, actually make an inner call to the function with the resolved arguments.
try {
+ env.enterScope(this, ast, env.getGlobals());
return invokeMethod.invoke(this, args);
} catch (InvocationTargetException x) {
Throwable e = x.getCause();
@@ -193,6 +196,7 @@
startTime,
ProfilerTask.SKYLARK_BUILTIN_FN,
this.getClass().getName() + "#" + getName());
+ env.exitScope();
}
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
index ed30671..25be3fd 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
@@ -15,18 +15,26 @@
package com.google.devtools.build.lib.syntax;
import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.events.EventKind;
import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.packages.CachingPackageLocator;
+import com.google.devtools.build.lib.syntax.Mutability.Freezable;
+import com.google.devtools.build.lib.syntax.Mutability.MutabilityException;
+import com.google.devtools.build.lib.util.Fingerprint;
+import com.google.devtools.build.lib.util.Pair;
+import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Deque;
+import java.io.Serializable;
import java.util.HashMap;
import java.util.HashSet;
-import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
@@ -34,54 +42,280 @@
import javax.annotation.Nullable;
/**
- * The BUILD environment.
+ * An Environment is the main entry point to evaluating code in the BUILD language or Skylark.
+ * It embodies all the state that is required to evaluate such code,
+ * except for the current instruction pointer, which is an {@link ASTNode}
+ * whose {@link Statement#exec exec} or {@link Expression#eval eval} method is invoked with
+ * this Environment, in a straightforward direct-style AST-walking interpreter.
+ * {@link Continuation}-s are explicitly represented, but only partly, with another part being
+ * implicit in a series of try-catch statements, to maintain the direct style. One notable trick
+ * is how a {@link UserDefinedFunction} implements returning values as the function catching a
+ * {@link ReturnStatement.ReturnException} thrown by a {@link ReturnStatement} in the body.
+ *
+ * <p>Every Environment has a {@link Mutability} field, and must be used within a function that
+ * creates and closes this {@link Mutability} with the try-with-resource pattern.
+ * This {@link Mutability} is also used when initializing mutable objects within that Environment;
+ * when closed at the end of the computation freezes the Environment and all those objects that
+ * then become forever immutable. The pattern enforces the discipline that there should be no
+ * dangling mutable Environment, or concurrency between interacting Environment-s.
+ * It is also an error to try to mutate an Environment and its objects from another Environment,
+ * before the {@link Mutability} is closed.
+ *
+ * <p>One creates an Environment using the {@link #builder} function, then
+ * populates it with {@link #setup}, {@link #setupDynamic} and sometimes {@link #setupOverride},
+ * before to evaluate code in it with {@link #eval}, or with {@link BuildFileAST#exec}
+ * (where the AST was obtained by passing a {@link ValidationEnvironment} constructed from the
+ * Environment to {@link BuildFileAST#parseBuildFile} or {@link BuildFileAST#parseSkylarkFile}).
+ * When the computation is over, the frozen Environment can still be queried with {@link #lookup}.
+ *
+ * <p>Final fields of an Environment represent its dynamic state, i.e. state that remains the same
+ * throughout a given evaluation context, and don't change with source code location,
+ * while mutable fields embody its static state, that change with source code location.
+ * The seeming paradox is that the words "dynamic" and "static" refer to the point of view
+ * of the source code, and here we have a dual point of view.
*/
-public class Environment {
-
- protected final Map<String, Object> env = new HashMap<>();
+public final class Environment implements Freezable, Serializable {
/**
- * The parent environment. For Skylark it's the global environment,
- * used for global read only variable lookup.
+ * A Frame is a Map of bindings, plus a {@link Mutability} and a parent Frame
+ * from which to inherit bindings.
+ *
+ * <p>A Frame contains bindings mapping variable name to variable value in a given scope.
+ * It may also inherit bindings from a parent Frame corresponding to a parent scope,
+ * which in turn may inherit bindings from its own parent, etc., transitively.
+ * Bindings may shadow bindings from the parent. In Skylark, you may only mutate
+ * bindings from the current Frame, which always got its {@link Mutability} with the
+ * current {@link Environment}; but future extensions may make it more like Python
+ * and allow mutation of bindings in outer Frame-s (or then again may not).
+ *
+ * <p>A Frame inherits the {@link Mutability} from the {@link Environment} in which it was
+ * originally created. When that {@link Environment} is finalized and its {@link Mutability}
+ * is closed, it becomes immutable, including the Frame, which can be shared in other
+ * {@link Environment}-s. Indeed, a {@link UserDefinedFunction} will close over the global
+ * Frame of its definition {@link Environment}, which will thus be reused (immutably)
+ * in all any {@link Environment} in which this function is called, so it's important to
+ * preserve the {@link Mutability} to make sure no Frame is modified after it's been finalized.
*/
- protected final Environment parent;
+ public static final class Frame implements Freezable {
+
+ private final Mutability mutability;
+ final Frame parent;
+ final Map<String, Object> bindings = new HashMap<>();
+
+ Frame(Mutability mutability, Frame parent) {
+ this.mutability = mutability;
+ this.parent = parent;
+ }
+
+ @Override
+ public final Mutability mutability() {
+ return mutability;
+ }
+
+ /**
+ * Gets a binding from the current frame or if not found its parent.
+ * @param varname the name of the variable to be bound
+ * @return the value bound to variable
+ */
+ public Object get(String varname) {
+ if (bindings.containsKey(varname)) {
+ return bindings.get(varname);
+ }
+ if (parent != null) {
+ return parent.get(varname);
+ }
+ return null;
+ }
+
+ /**
+ * Modifies a binding in the current Frame.
+ * Does not try to modify an inherited binding.
+ * This will shadow any inherited binding, which may be an error
+ * that you want to guard against before calling this function.
+ * @param env the Environment attempting the mutation
+ * @param varname the name of the variable to be bound
+ * @param value the value to bind to the variable
+ */
+ public void put(Environment env, String varname, Object value)
+ throws MutabilityException {
+ Mutability.checkMutable(this, env);
+ bindings.put(varname, value);
+ }
+
+ /**
+ * Adds the variable names of this Frame and its transitive parents to the given set.
+ * This provides a O(n) way of extracting the list of all variables visible in an Environment.
+ * @param vars the set of visible variables in the Environment, being computed.
+ */
+ public void addVariableNamesTo(Set<String> vars) {
+ vars.addAll(bindings.keySet());
+ if (parent != null) {
+ parent.addVariableNamesTo(vars);
+ }
+ }
+
+ public Set<String> getDirectVariableNames() {
+ return bindings.keySet();
+ }
+
+ @Override
+ public String toString() {
+ String prefix = "Frame";
+ StringBuilder sb = new StringBuilder();
+ for (Frame f = this; f != null; f = f.parent) {
+ Printer.formatTo(sb, "%s%s%r",
+ ImmutableList.<Object>of(prefix, f.mutability(), f.bindings));
+ prefix = "=>";
+ }
+ return sb.toString();
+ }
+ }
/**
- * Map from a Skylark extension to an environment, which contains all symbols defined in the
- * extension.
+ * A Continuation contains data saved during a function call and restored when the function exits.
*/
- protected Map<PathFragment, SkylarkEnvironment> importedExtensions;
+ private static final class Continuation {
+ /** The {@link BaseFunction} being evaluated that will return into this Continuation. */
+ BaseFunction function;
+
+ /** The {@link FuncallExpression} to which this Continuation will return. */
+ FuncallExpression caller;
+
+ /** The next Continuation after this Continuation. */
+ @Nullable Continuation continuation;
+
+ /** The lexical Frame of the caller. */
+ Frame lexicalFrame;
+
+ /** The global Frame of the caller. */
+ Frame globalFrame;
+
+ /** The set of known global variables of the caller. */
+ @Nullable Set<String> knownGlobalVariables;
+
+ /** Whether the caller is in Skylark mode. */
+ boolean isSkylark;
+
+ Continuation(
+ Continuation continuation,
+ BaseFunction function,
+ FuncallExpression caller,
+ Frame lexicalFrame,
+ Frame globalFrame,
+ Set<String> knownGlobalVariables,
+ boolean isSkylark) {
+ this.continuation = continuation;
+ this.function = function;
+ this.caller = caller;
+ this.lexicalFrame = lexicalFrame;
+ this.globalFrame = globalFrame;
+ this.isSkylark = isSkylark;
+ }
+ }
/**
- * A set of variables propagating through function calling. It's only used to call
- * native rules from Skylark build extensions.
+ * Static Frame for lexical variables that are always looked up in the current Environment
+ * or for the definition Environment of the function currently being evaluated.
*/
- protected Set<String> propagatingVariables = new HashSet<>();
+ private Frame lexicalFrame;
- // Only used in the global environment.
- // TODO(bazel-team): make this a final field part of constructor.
- private boolean isLoadingPhase = false;
+ /**
+ * Static Frame for global variables; either the current lexical Frame if evaluation is currently
+ * happening at the global scope of a BUILD file, or the global Frame at the time of function
+ * definition if evaluation is currently happening in the body of a function. Thus functions can
+ * close over other functions defined in the same file.
+ */
+ private Frame globalFrame;
+
+ /**
+ * Dynamic Frame for variables that are always looked up in the runtime Environment,
+ * and never in the lexical or "global" Environment as it was at the time of function definition.
+ * For instance, PACKAGE_NAME.
+ */
+ private final Frame dynamicFrame;
+
+ /**
+ * An EventHandler for errors and warnings. This is not used in the BUILD language,
+ * however it might be used in Skylark code called from the BUILD language, so shouldn't be null.
+ */
+ private final EventHandler eventHandler;
+
+ /**
+ * For each imported extensions, a global Skylark frame from which to load() individual bindings.
+ */
+ private final Map<PathFragment, Environment> importedExtensions;
+
+ /**
+ * Is this Environment being executed in Skylark context?
+ */
+ private boolean isSkylark;
+
+ /**
+ * Is this Environment being executed during the loading phase?
+ * Many builtin functions are only enabled during the loading phase, and check this flag.
+ */
+ private final boolean isLoadingPhase;
+
+ /**
+ * When in a lexical (Skylark) Frame, this set contains the variable names that are global,
+ * as determined not by global declarations (not currently supported),
+ * but by previous lookups that ended being global or dynamic.
+ * This is necessary because if in a function definition something
+ * reads a global variable after which a local variable with the same name is assigned an
+ * Exception needs to be thrown.
+ */
+ @Nullable private Set<String> knownGlobalVariables;
+
+ /**
+ * When in a lexical (Skylark) frame, this lists the names of the functions in the call stack.
+ * We currently use it to artificially disable recursion.
+ */
+ @Nullable private Continuation continuation;
+
+ /**
+ * Enters a scope by saving state to a new Continuation
+ * @param function the function whose scope to enter
+ * @param caller the source AST node for the caller
+ * @param globals the global Frame that this function closes over from its definition Environment
+ */
+ void enterScope(BaseFunction function, FuncallExpression caller, Frame globals) {
+ continuation = new Continuation(
+ continuation, function, caller, lexicalFrame, globalFrame, knownGlobalVariables, isSkylark);
+ lexicalFrame = new Frame(mutability(), null);
+ globalFrame = globals;
+ knownGlobalVariables = new HashSet<String>();
+ isSkylark = true;
+ }
+
+ /**
+ * Exits a scope by restoring state from the current continuation
+ */
+ void exitScope() {
+ Preconditions.checkNotNull(continuation);
+ lexicalFrame = continuation.lexicalFrame;
+ globalFrame = continuation.globalFrame;
+ knownGlobalVariables = continuation.knownGlobalVariables;
+ isSkylark = continuation.isSkylark;
+ continuation = continuation.continuation;
+ }
+
+ /**
+ * When evaluating code from a file, this contains a hash of the file.
+ */
+ @Nullable private String fileContentHashCode;
/**
* Is this Environment being evaluated during the loading phase?
- * This is fixed during environment setup, and enables various functions
+ * This is fixed during Environment setup, and enables various functions
* that are not available during the analysis phase.
- * @return true if this environment corresponds to code during the loading phase.
+ * @return true if this Environment corresponds to code during the loading phase.
*/
- boolean isLoadingPhase() {
+ private boolean isLoadingPhase() {
return isLoadingPhase;
}
/**
- * Enable loading phase only functions in this Environment.
- * This should only be done during setup before code is evaluated.
- */
- public void setLoadingPhase() {
- isLoadingPhase = true;
- }
-
- /**
- * Checks that the current Evaluation context is in loading phase.
+ * Checks that the current Environment is in the loading phase.
* @param symbol name of the function being only authorized thus.
*/
public void checkLoadingPhase(String symbol, Location loc) throws EvalException {
@@ -91,168 +325,378 @@
}
/**
- * Is this a global environment?
- * @return true if this is a global (top-level) environment
- * as opposed to inside the body of a function
+ * Is this a global Environment?
+ * @return true if the current code is being executed at the top-level,
+ * as opposed to inside the body of a function.
*/
- public boolean isGlobal() {
- return true;
+ boolean isGlobal() {
+ return lexicalFrame == null;
}
/**
- * An EventHandler for errors and warnings. This is not used in the BUILD language,
- * however it might be used in Skylark code called from the BUILD language.
+ * Is the current code Skylark?
+ * @return true if Skylark was enabled when this code was read.
*/
- @Nullable protected EventHandler eventHandler;
-
- /**
- * A stack trace containing the current history of functions and the calling rule.
- *
- * <p>For the rule, the stack trace has two elements: one for the call to the rule in the BUILD
- * file and one for the actual rule implementation.
- */
- private Deque<StackTraceElement> stackTrace;
-
- /**
- * Constructs an empty root non-Skylark environment.
- * The root environment is also the global environment.
- */
- public Environment(Deque<StackTraceElement> stackTrace) {
- this.parent = null;
- this.importedExtensions = new HashMap<>();
- this.stackTrace = stackTrace;
- setupGlobal();
- }
-
- public Environment() {
- this(new LinkedList<StackTraceElement>());
+ // TODO(bazel-team): Delete this function.
+ // This function is currently used in various functions that change their behavior with respect to
+ // lists depending on the Skylark-ness of the code; lists should be unified between the two modes.
+ boolean isSkylark() {
+ return isSkylark;
}
/**
- * Constructs an empty child environment.
+ * Is the caller of the current function executing Skylark code?
+ * @return true if this is skylark was enabled when this code was read.
*/
- public Environment(Environment parent, Deque<StackTraceElement> stackTrace) {
- Preconditions.checkNotNull(parent);
- this.parent = parent;
- this.importedExtensions = new HashMap<>();
- this.stackTrace = stackTrace;
+ // TODO(bazel-team): Delete this function.
+ // This function is currently used by MethodLibrary to modify behavior of lists
+ // depending on the Skylark-ness of the code; lists should be unified between the two modes.
+ boolean isCallerSkylark() {
+ return continuation.isSkylark;
}
- public Environment(Environment parent) {
- this(parent, new LinkedList<StackTraceElement>());
+ @Override
+ public Mutability mutability() {
+ // the mutability of the environment is that of its dynamic frame.
+ return dynamicFrame.mutability();
}
/**
- * Constructs an empty child environment with an EventHandler.
+ * @return the current Frame, in which variable side-effects happen.
*/
- public Environment(Environment parent, EventHandler eventHandler) {
- this(parent);
- this.eventHandler = Preconditions.checkNotNull(eventHandler);
+ private Frame currentFrame() {
+ return isGlobal() ? globalFrame : lexicalFrame;
}
+ /**
+ * @return the global variables for the Environment (not including dynamic bindings).
+ */
+ public Frame getGlobals() {
+ return globalFrame;
+ }
+
+ /**
+ * Returns an EventHandler for errors and warnings.
+ * The BUILD language doesn't use it directly, but can call Skylark code that does use it.
+ * @return an EventHandler
+ */
public EventHandler getEventHandler() {
return eventHandler;
}
- // Sets up the global environment
- private void setupGlobal() {
- // In Python 2.x, True and False are global values and can be redefined by the user.
- // In Python 3.x, they are keywords. We implement them as values, for the sake of
- // simplicity. We define them as Boolean objects.
- update("False", Runtime.FALSE);
- update("True", Runtime.TRUE);
- update("None", Runtime.NONE);
+ /**
+ * @return the current stack trace as a list of functions.
+ */
+ public ImmutableList<BaseFunction> getStackTrace() {
+ ImmutableList.Builder<BaseFunction> builder = new ImmutableList.Builder<>();
+ for (Continuation k = continuation; k != null; k = k.continuation) {
+ builder.add(k.function);
+ }
+ return builder.build().reverse();
}
- public boolean isSkylark() {
- return false;
+ /**
+ * Return the name of the top-level function being called and the location of the call.
+ */
+ public Pair<BaseFunction, Location> getTopCall() {
+ Continuation continuation = this.continuation;
+ if (continuation == null) {
+ return null;
+ }
+ while (continuation.continuation != null) {
+ continuation = continuation.continuation;
+ }
+ return new Pair<>(continuation.function, continuation.caller.getLocation());
}
- protected boolean hasVariable(String varname) {
- return env.containsKey(varname);
+ /**
+ * Constructs an Environment.
+ * This is the main, most basic constructor.
+ * @param globalFrame a frame for the global Environment
+ * @param dynamicFrame a frame for the dynamic Environment
+ * @param eventHandler an EventHandler for warnings, errors, etc
+ * @param importedExtensions frames for extensions from which to import bindings with load()
+ * @param isSkylark true if in Skylark context
+ * @param fileContentHashCode a hash for the source file being evaluated, if any
+ * @param isLoadingPhase true if in loading phase
+ */
+ private Environment(
+ Frame globalFrame,
+ Frame dynamicFrame,
+ EventHandler eventHandler,
+ Map<PathFragment, Environment> importedExtensions,
+ boolean isSkylark,
+ @Nullable String fileContentHashCode,
+ boolean isLoadingPhase) {
+ this.globalFrame = Preconditions.checkNotNull(globalFrame);
+ this.dynamicFrame = Preconditions.checkNotNull(dynamicFrame);
+ Preconditions.checkArgument(globalFrame.mutability().isMutable());
+ Preconditions.checkArgument(dynamicFrame.mutability().isMutable());
+ this.eventHandler = eventHandler;
+ this.importedExtensions = importedExtensions;
+ this.isSkylark = isSkylark;
+ this.fileContentHashCode = fileContentHashCode;
+ this.isLoadingPhase = isLoadingPhase;
+ }
+
+ /**
+ * A Builder class for Environment
+ */
+ public static class Builder {
+ private final Mutability mutability;
+ private boolean isSkylark = false;
+ private boolean isLoadingPhase = false;
+ @Nullable private Frame parent;
+ @Nullable private EventHandler eventHandler;
+ @Nullable private Map<PathFragment, Environment> importedExtensions;
+ @Nullable private String fileContentHashCode;
+
+ Builder(Mutability mutability) {
+ this.mutability = mutability;
+ }
+
+ /** Enables Skylark for code read in this Environment. */
+ public Builder setSkylark() {
+ Preconditions.checkState(!isSkylark);
+ isSkylark = true;
+ return this;
+ }
+
+ /** Enables loading phase only functions in this Environment. */
+ public Builder setLoadingPhase() {
+ Preconditions.checkState(!isLoadingPhase);
+ isLoadingPhase = true;
+ return this;
+ }
+
+ /** Inherits global bindings from the given parent Frame. */
+ public Builder setGlobals(Frame parent) {
+ Preconditions.checkState(this.parent == null);
+ this.parent = parent;
+ return this;
+ }
+
+ /** Sets an EventHandler for errors and warnings. */
+ public Builder setEventHandler(EventHandler eventHandler) {
+ Preconditions.checkState(this.eventHandler == null);
+ this.eventHandler = eventHandler;
+ return this;
+ }
+
+ /** Declares imported extensions for load() statements. */
+ public Builder setImportedExtensions (Map<PathFragment, Environment> importedExtensions) {
+ Preconditions.checkState(this.importedExtensions == null);
+ this.importedExtensions = importedExtensions;
+ return this;
+ }
+
+ /** Declares content hash for the source file for this Environment. */
+ public Builder setFileContentHashCode(String fileContentHashCode) {
+ this.fileContentHashCode = fileContentHashCode;
+ return this;
+ }
+
+ /** Builds the Environment. */
+ public Environment build() {
+ Preconditions.checkArgument(mutability.isMutable());
+ if (parent != null) {
+ Preconditions.checkArgument(!parent.mutability().isMutable());
+ }
+ Frame globalFrame = new Frame(mutability, parent);
+ Frame dynamicFrame = new Frame(mutability, null);
+ if (importedExtensions == null) {
+ importedExtensions = ImmutableMap.of();
+ }
+ Environment env = new Environment(
+ globalFrame,
+ dynamicFrame,
+ eventHandler,
+ importedExtensions,
+ isSkylark,
+ fileContentHashCode,
+ isLoadingPhase);
+ return env;
+ }
+ }
+
+ public static Builder builder(Mutability mutability) {
+ return new Builder(mutability);
+ }
+
+ /**
+ * Sets a binding for a special dynamic variable in this Environment.
+ * This is not for end-users, and will throw an AssertionError in case of conflict.
+ * @param varname the name of the dynamic variable to be bound
+ * @param value a value to bind to the variable
+ * @return this Environment, in fluid style
+ */
+ public Environment setupDynamic(String varname, Object value) {
+ if (dynamicFrame.get(varname) != null) {
+ throw new AssertionError(
+ String.format("Trying to bind dynamic variable '%s' but it is already bound",
+ varname));
+ }
+ if (lexicalFrame != null && lexicalFrame.get(varname) != null) {
+ throw new AssertionError(
+ String.format("Trying to bind dynamic variable '%s' but it is already bound lexically",
+ varname));
+ }
+ if (globalFrame.get(varname) != null) {
+ throw new AssertionError(
+ String.format("Trying to bind dynamic variable '%s' but it is already bound globally",
+ varname));
+ }
+ try {
+ dynamicFrame.put(this, varname, value);
+ } catch (MutabilityException e) {
+ // End users don't have access to setupDynamic, and it is an implementation error
+ // if we encounter a mutability exception.
+ throw new AssertionError(
+ Printer.format(
+ "Trying to bind dynamic variable '%s' in frozen environment %r", varname, this),
+ e);
+ }
+ return this;
+ }
+
+
+ /**
+ * Modifies a binding in the current Frame of this Environment, as would an
+ * {@link AssignmentStatement}. Does not try to modify an inherited binding.
+ * This will shadow any inherited binding, which may be an error
+ * that you want to guard against before calling this function.
+ * @param varname the name of the variable to be bound
+ * @param value the value to bind to the variable
+ * @return this Environment, in fluid style
+ */
+ public Environment update(String varname, Object value) throws EvalException {
+ Preconditions.checkNotNull(value, "update(value == null)");
+ // prevents clashes between static and dynamic variables.
+ if (dynamicFrame.get(varname) != null) {
+ throw new EvalException(
+ null, String.format("Trying to update special read-only global variable '%s'", varname));
+ }
+ if (isKnownGlobalVariable(varname)) {
+ throw new EvalException(
+ null, String.format("Trying to update read-only global variable '%s'", varname));
+ }
+ try {
+ currentFrame().put(this, varname, Preconditions.checkNotNull(value));
+ } catch (MutabilityException e) {
+ // Note that since at this time we don't accept the global keyword, and don't have closures,
+ // end users should never be able to mutate a frozen Environment, and a MutabilityException
+ // is therefore a failed assertion for Bazel. However, it is possible to shadow a binding
+ // imported from a parent Environment by updating the current Environment, which will not
+ // trigger a MutabilityException.
+ throw new AssertionError(
+ Printer.format("Can't update %s to %r in frozen environment", varname, value),
+ e);
+ }
+ return this;
+ }
+
+ private boolean hasVariable(String varname) {
+ try {
+ lookup(varname);
+ return true;
+ } catch (NoSuchVariableException e) {
+ return false;
+ }
+ }
+
+ /**
+ * Initializes a binding in this Environment. It is an error if the variable is already bound.
+ * This is not for end-users, and will throw an AssertionError in case of conflict.
+ * @param varname the name of the variable to be bound
+ * @param value the value to bind to the variable
+ * @return this Environment, in fluid style
+ */
+ public Environment setup(String varname, Object value) {
+ if (hasVariable(varname)) {
+ throw new AssertionError(String.format("variable '%s' already bound", varname));
+ }
+ return setupOverride(varname, value);
+ }
+
+ /**
+ * Initializes a binding in this environment. Overrides any previous binding.
+ * This is not for end-users, and will throw an AssertionError in case of conflict.
+ * @param varname the name of the variable to be bound
+ * @param value the value to bind to the variable
+ * @return this Environment, in fluid style
+ */
+ public Environment setupOverride(String varname, Object value) {
+ try {
+ return update(varname, value);
+ } catch (EvalException ee) {
+ throw new AssertionError(ee);
+ }
}
/**
* @return the value from the environment whose name is "varname".
* @throws NoSuchVariableException if the variable is not defined in the Environment.
- *
*/
public Object lookup(String varname) throws NoSuchVariableException {
- Object value = env.get(varname);
- if (value == null) {
- if (parent != null) {
- return parent.lookup(varname);
+ // Which Frame to lookup first doesn't matter because update prevents clashes.
+ if (lexicalFrame != null) {
+ Object lexicalValue = lexicalFrame.get(varname);
+ if (lexicalValue != null) {
+ return lexicalValue;
}
+ }
+ Object globalValue = globalFrame.get(varname);
+ Object dynamicValue = dynamicFrame.get(varname);
+ if (globalValue == null && dynamicValue == null) {
throw new NoSuchVariableException(varname);
}
- return value;
+ if (knownGlobalVariables != null) {
+ knownGlobalVariables.add(varname);
+ }
+ if (globalValue != null) {
+ return globalValue;
+ }
+ return dynamicValue;
}
/**
- * Like <code>lookup(String)</code>, but instead of throwing an exception in
- * the case where "varname" is not defined, "defaultValue" is returned instead.
- *
+ * Like {@link #lookup(String)}, but instead of throwing an exception in the case
+ * where <code>varname</code> is not defined, <code>defaultValue</code> is returned instead.
*/
public Object lookup(String varname, Object defaultValue) {
- Object value = env.get(varname);
- if (value == null) {
- if (parent != null) {
- return parent.lookup(varname, defaultValue);
- }
+ Preconditions.checkState(!isSkylark);
+ try {
+ return lookup(varname);
+ } catch (NoSuchVariableException e) {
return defaultValue;
}
- return value;
}
/**
- * Updates the value of variable "varname" in the environment, corresponding
- * to an {@link AssignmentStatement}.
+ * @return true if varname is a known global variable,
+ * because it has been read in the context of the current function.
*/
- public Environment update(String varname, Object value) {
- Preconditions.checkNotNull(value, "update(value == null)");
- env.put(varname, value);
- return this;
+ boolean isKnownGlobalVariable(String varname) {
+ return knownGlobalVariables != null && knownGlobalVariables.contains(varname);
+ }
+
+ public void handleEvent(Event event) {
+ eventHandler.handle(event);
}
/**
- * Same as {@link #update}, but also marks the variable propagating, meaning it will
- * be present in the execution environment of a UserDefinedFunction called from this
- * Environment. Using this method is discouraged.
- */
- public void updateAndPropagate(String varname, Object value) {
- update(varname, value);
- propagatingVariables.add(varname);
- }
-
- /**
- * Remove the variable from the environment, returning
- * any previous mapping (null if there was none).
- */
- public Object remove(String varname) {
- return env.remove(varname);
- }
-
- /**
- * Returns the (immutable) set of names of all variables directly defined in this environment.
- */
- public Set<String> getDirectVariableNames() {
- return env.keySet();
- }
-
- /**
- * Returns the (immutable) set of names of all variables defined in this
- * environment. Exposed for testing; not very efficient!
+ * @return the (immutable) set of names of all variables defined in this
+ * Environment. Exposed for testing.
*/
@VisibleForTesting
public Set<String> getVariableNames() {
- if (parent == null) {
- return env.keySet();
- } else {
- Set<String> vars = new HashSet<>();
- vars.addAll(env.keySet());
- vars.addAll(parent.getVariableNames());
- return vars;
+ Set<String> vars = new HashSet<>();
+ if (lexicalFrame != null) {
+ lexicalFrame.addVariableNamesTo(vars);
}
+ globalFrame.addVariableNamesTo(vars);
+ dynamicFrame.addVariableNamesTo(vars);
+ return vars;
}
@Override
@@ -268,23 +712,29 @@
@Override
public String toString() {
StringBuilder out = new StringBuilder();
- out.append("Environment{");
- List<String> keys = new ArrayList<>(env.keySet());
- Collections.sort(keys);
- for (String key : keys) {
- out.append(key).append(" -> ").append(env.get(key)).append(", ");
- }
- out.append("}");
- if (parent != null) {
- out.append("=>");
- out.append(parent);
- }
+ out.append("Environment(lexicalFrame=");
+ out.append(lexicalFrame);
+ out.append(", globalFrame=");
+ out.append(globalFrame);
+ out.append(", dynamicFrame=");
+ out.append(dynamicFrame);
+ out.append(", eventHandler.getClass()=");
+ out.append(eventHandler.getClass());
+ out.append(", importedExtensions=");
+ out.append(importedExtensions);
+ out.append(", isSkylark=");
+ out.append(isSkylark);
+ out.append(", fileContentHashCode=");
+ out.append(fileContentHashCode);
+ out.append(", isLoadingPhase=");
+ out.append(isLoadingPhase);
+ out.append(")");
return out.toString();
}
/**
- * An exception thrown when an attempt is made to lookup a non-existent
- * variable in the environment.
+ * An Exception thrown when an attempt is made to lookup a non-existent
+ * variable in the Environment.
*/
public static class NoSuchVariableException extends Exception {
NoSuchVariableException(String variable) {
@@ -293,7 +743,7 @@
}
/**
- * An exception thrown when an attempt is made to import a symbol from a file
+ * An Exception thrown when an attempt is made to import a symbol from a file
* that was not properly loaded.
*/
public static class LoadFailedException extends Exception {
@@ -303,78 +753,156 @@
}
}
- public void setImportedExtensions(Map<PathFragment, SkylarkEnvironment> importedExtensions) {
- this.importedExtensions = importedExtensions;
- }
-
public void importSymbol(PathFragment extension, Identifier symbol, String nameInLoadedFile)
throws NoSuchVariableException, LoadFailedException {
+ Preconditions.checkState(isGlobal()); // loading is only allowed at global scope.
+
if (!importedExtensions.containsKey(extension)) {
throw new LoadFailedException(extension.toString());
}
Object value = importedExtensions.get(extension).lookup(nameInLoadedFile);
- if (!isSkylark()) {
+ // TODO(bazel-team): Unify data structures between Skylark and BUILD,
+ // and stop doing the conversions below:
+ if (!isSkylark) {
value = SkylarkType.convertFromSkylark(value);
}
- update(symbol.getName(), value);
- }
-
- public ImmutableList<StackTraceElement> getStackTrace() {
- return ImmutableList.copyOf(stackTrace);
- }
-
- protected Deque<StackTraceElement> getCopyOfStackTrace() {
- return new LinkedList<>(stackTrace);
- }
-
- /**
- * Adds the given element to the stack trace (iff the stack is empty) and returns whether it was
- * successful.
- */
- public boolean tryAddingStackTraceRoot(StackTraceElement element) {
- if (stackTrace.isEmpty()) {
- stackTrace.add(element);
- return true;
+ try {
+ update(symbol.getName(), value);
+ } catch (EvalException e) {
+ throw new LoadFailedException(extension.toString());
}
- return false;
- }
-
- public void addToStackTrace(StackTraceElement element) {
- stackTrace.add(element);
}
/**
- * Removes the only remaining element from the stack trace.
- *
- * <p>This particular element describes the outer-most calling function (usually a rule).
- *
- * <p> This method is required since {@link FuncallExpression} does not create a new {@link
- * Environment}, hence it has to add and remove its {@link StackTraceElement} from an existing
- * one.
+ * Returns a hash code calculated from the hash code of this Environment and the
+ * transitive closure of other Environments it loads.
*/
- public void removeStackTraceRoot() {
- Preconditions.checkArgument(stackTrace.size() == 1);
- stackTrace.clear();
+ // TODO(bazel-team): to avoid O(n^2) worst case, cache this transitive hash code.
+ public String getTransitiveFileContentHashCode() {
+ Fingerprint fingerprint = new Fingerprint();
+ fingerprint.addString(Preconditions.checkNotNull(fileContentHashCode));
+ // Calculate a new hash from the hash of the loaded Environments.
+ for (Environment env : importedExtensions.values()) {
+ fingerprint.addString(env.getTransitiveFileContentHashCode());
+ }
+ return fingerprint.hexDigestAndReset();
}
- public void removeStackTraceElement() {
- // TODO(fwe): find out why the precond doesn't work
- // Preconditions.checkArgument(stackTrace.size() > 1);
- stackTrace.removeLast();
+
+ /** A read-only Environment.Frame with global constants in it only */
+ public static final Frame CONSTANTS_ONLY = createConstantsGlobals();
+
+ /** A read-only Environment.Frame with initial globals for the BUILD language */
+ public static final Frame BUILD = createBuildGlobals();
+
+ /** A read-only Environment.Frame with initial globals for Skylark */
+ public static final Frame SKYLARK = createSkylarkGlobals();
+
+ private static Environment.Frame createConstantsGlobals() {
+ try (Mutability mutability = Mutability.create("CONSTANTS")) {
+ Environment env = Environment.builder(mutability).build();
+ Runtime.setupConstants(env);
+ return env.getGlobals();
+ }
+ }
+
+ private static Environment.Frame createBuildGlobals() {
+ try (Mutability mutability = Mutability.create("BUILD")) {
+ Environment env = Environment.builder(mutability).build();
+ Runtime.setupConstants(env);
+ Runtime.setupMethodEnvironment(env, MethodLibrary.buildGlobalFunctions);
+ return env.getGlobals();
+ }
+ }
+
+ private static Environment.Frame createSkylarkGlobals() {
+ try (Mutability mutability = Mutability.create("SKYLARK")) {
+ Environment env = Environment.builder(mutability).setSkylark().build();
+ Runtime.setupConstants(env);
+ Runtime.setupMethodEnvironment(env, MethodLibrary.skylarkGlobalFunctions);
+ return env.getGlobals();
+ }
+ }
+
+
+ /**
+ * The fail fast handler, which throws a AssertionError whenever an error or warning occurs.
+ */
+ public static final EventHandler FAIL_FAST_HANDLER = new EventHandler() {
+ @Override
+ public void handle(Event event) {
+ Preconditions.checkArgument(
+ !EventKind.ERRORS_AND_WARNINGS.contains(event.getKind()), event);
+ }
+ };
+
+ /** Mock package locator class */
+ private static final class EmptyPackageLocator implements CachingPackageLocator {
+ @Override
+ public Path getBuildFileForPackage(PackageIdentifier packageName) {
+ return null;
+ }
+ }
+
+ /** A mock package locator */
+ @VisibleForTesting
+ static final CachingPackageLocator EMPTY_PACKAGE_LOCATOR = new EmptyPackageLocator();
+
+ /**
+ * Creates a Lexer without a supporting file.
+ * @param input a list of lines of code
+ */
+ @VisibleForTesting
+ Lexer createLexer(String... input) {
+ return new Lexer(ParserInputSource.create(Joiner.on("\n").join(input), null),
+ eventHandler);
}
/**
- * Returns whether the given {@link BaseFunction} is part of this {@link Environment}'s stack
- * trace.
+ * Parses some String input without a supporting file, returning statements and comments.
+ * @param input a list of lines of code
*/
- public boolean stackTraceContains(BaseFunction function) {
- for (StackTraceElement element : stackTrace) {
- if (element.hasFunction(function)) {
- return true;
+ @VisibleForTesting
+ Parser.ParseResult parseFileWithComments(String... input) {
+ return isSkylark
+ ? Parser.parseFileForSkylark(
+ createLexer(input),
+ eventHandler,
+ EMPTY_PACKAGE_LOCATOR,
+ new ValidationEnvironment(this))
+ : Parser.parseFile(
+ createLexer(input),
+ eventHandler,
+ EMPTY_PACKAGE_LOCATOR,
+ /*parsePython=*/false);
+ }
+
+ /**
+ * Parses some String input without a supporting file, returning statements only.
+ * @param input a list of lines of code
+ */
+ @VisibleForTesting
+ List<Statement> parseFile(String... input) {
+ return parseFileWithComments(input).statements;
+ }
+
+ /**
+ * Evaluates code some String input without a supporting file.
+ * @param input a list of lines of code to evaluate
+ * @return the value of the last statement if it's an Expression or else null
+ */
+ @Nullable public Object eval(String... input) throws EvalException, InterruptedException {
+ Object last = null;
+ for (Statement statement : parseFile(input)) {
+ if (statement instanceof ExpressionStatement) {
+ last = ((ExpressionStatement) statement).getExpression().eval(this);
+ } else {
+ statement.exec(this);
+ last = null;
}
}
- return false;
+ return last;
}
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/EvalExceptionWithStackTrace.java b/src/main/java/com/google/devtools/build/lib/syntax/EvalExceptionWithStackTrace.java
index 82ca835..714556e 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/EvalExceptionWithStackTrace.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/EvalExceptionWithStackTrace.java
@@ -200,7 +200,7 @@
return String.format(
"\tFile \"%s\", line %d, in %s%n\t\t%s",
printPath(location.getPath()),
- location.getStartLineAndColumn().getLine(),
+ location.getStartLine(),
element.getLabel(),
element.getCause().getLabel());
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java b/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java
deleted file mode 100644
index 6a24cb3..0000000
--- a/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java
+++ /dev/null
@@ -1,195 +0,0 @@
-// Copyright 2015 Google Inc. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.google.devtools.build.lib.syntax;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.events.Event;
-import com.google.devtools.build.lib.events.EventHandler;
-import com.google.devtools.build.lib.events.EventKind;
-import com.google.devtools.build.lib.packages.CachingPackageLocator;
-import com.google.devtools.build.lib.syntax.Environment.NoSuchVariableException;
-import com.google.devtools.build.lib.vfs.Path;
-
-import java.util.List;
-
-import javax.annotation.Nullable;
-
-/**
- * Context for the evaluation of programs.
- */
-public final class EvaluationContext {
-
- @Nullable private EventHandler eventHandler;
- private Environment env;
- @Nullable private ValidationEnvironment validationEnv;
- private boolean parsePython;
-
- private EvaluationContext(EventHandler eventHandler, Environment env,
- @Nullable ValidationEnvironment validationEnv, boolean parsePython) {
- this.eventHandler = eventHandler;
- this.env = env;
- this.validationEnv = validationEnv;
- this.parsePython = parsePython;
- }
-
- /**
- * The fail fast handler, which throws a runtime exception whenever we encounter an error event.
- */
- public static final EventHandler FAIL_FAST_HANDLER = new EventHandler() {
- @Override
- public void handle(Event event) {
- Preconditions.checkArgument(
- !EventKind.ERRORS_AND_WARNINGS.contains(event.getKind()), event);
- }
- };
-
- public static EvaluationContext newBuildContext(EventHandler eventHandler, Environment env,
- boolean parsePython) {
- return new EvaluationContext(eventHandler, env, null, parsePython);
- }
-
- public static EvaluationContext newBuildContext(EventHandler eventHandler, Environment env) {
- return newBuildContext(eventHandler, env, false);
- }
-
- public static EvaluationContext newBuildContext(EventHandler eventHandler) {
- return newBuildContext(eventHandler, new Environment());
- }
-
- public static EvaluationContext newSkylarkContext(
- Environment env, ValidationEnvironment validationEnv) {
- return new EvaluationContext(env.getEventHandler(), env, validationEnv, false);
- }
-
- public static EvaluationContext newSkylarkContext(EventHandler eventHandler) {
- return newSkylarkContext(new SkylarkEnvironment(eventHandler), new ValidationEnvironment());
- }
-
- /** Base context for Skylark evaluation for internal use only, while initializing builtins */
- static final EvaluationContext SKYLARK_INITIALIZATION = newSkylarkContext(FAIL_FAST_HANDLER);
-
- @VisibleForTesting
- public Environment getEnvironment() {
- return env;
- }
-
- /** Mock package locator */
- private static final class EmptyPackageLocator implements CachingPackageLocator {
- @Override
- public Path getBuildFileForPackage(PackageIdentifier packageName) {
- return null;
- }
- }
-
- /** An empty package locator */
- private static final CachingPackageLocator EMPTY_PACKAGE_LOCATOR = new EmptyPackageLocator();
-
- /** Create a Lexer without a supporting file */
- @VisibleForTesting
- Lexer createLexer(String... input) {
- return new Lexer(ParserInputSource.create(Joiner.on("\n").join(input), null),
- eventHandler);
- }
-
- /** Is this a Skylark evaluation context? */
- public boolean isSkylark() {
- return env.isSkylark();
- }
-
- /** Parse a string without a supporting file, returning statements and comments */
- @VisibleForTesting
- Parser.ParseResult parseFileWithComments(String... input) {
- return isSkylark()
- ? Parser.parseFileForSkylark(createLexer(input), eventHandler, null, validationEnv)
- : Parser.parseFile(createLexer(input), eventHandler, EMPTY_PACKAGE_LOCATOR, parsePython);
- }
-
- /** Parse a string without a supporting file, returning statements only */
- @VisibleForTesting
- List<Statement> parseFile(String... input) {
- return parseFileWithComments(input).statements;
- }
-
- /** Parse an Expression from string without a supporting file */
- @VisibleForTesting
- Expression parseExpression(String... input) {
- return Parser.parseExpression(createLexer(input), eventHandler);
- }
-
- /** Evaluate an Expression */
- @VisibleForTesting
- Object evalExpression(Expression expression) throws EvalException, InterruptedException {
- return expression.eval(env);
- }
-
- /** Evaluate an Expression as parsed from String-s */
- Object evalExpression(String... input) throws EvalException, InterruptedException {
- return evalExpression(parseExpression(input));
- }
-
- /** Parse a build (not Skylark) Statement from string without a supporting file */
- @VisibleForTesting
- Statement parseStatement(String... input) {
- return Parser.parseStatement(createLexer(input), eventHandler);
- }
-
- /**
- * Evaluate a Statement
- * @param statement the Statement
- * @return the value of the evaluation, if it's an Expression, or else null
- */
- @Nullable private Object eval(Statement statement) throws EvalException, InterruptedException {
- if (statement instanceof ExpressionStatement) {
- return evalExpression(((ExpressionStatement) statement).getExpression());
- }
- statement.exec(env);
- return null;
- }
-
- /**
- * Evaluate a list of Statement-s
- * @return the value of the last statement if it's an Expression or else null
- */
- @Nullable private Object eval(List<Statement> statements)
- throws EvalException, InterruptedException {
- Object last = null;
- for (Statement statement : statements) {
- last = eval(statement);
- }
- return last;
- }
-
- /** Update a variable in the environment, in fluent style */
- public EvaluationContext update(String varname, Object value) throws EvalException {
- env.update(varname, value);
- if (validationEnv != null) {
- validationEnv.declare(varname, null);
- }
- return this;
- }
-
- /** Lookup a variable in the environment */
- public Object lookup(String varname) throws NoSuchVariableException {
- return env.lookup(varname);
- }
-
- /** Evaluate a series of statements */
- public Object eval(String... input) throws EvalException, InterruptedException {
- return eval(parseFile(input));
- }
-}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Expression.java b/src/main/java/com/google/devtools/build/lib/syntax/Expression.java
index b7842d4..1886843 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Expression.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Expression.java
@@ -42,8 +42,8 @@
/**
* Returns the inferred type of the result of the Expression.
*
- * <p>Checks the semantics of the Expression using the SkylarkEnvironment according to
- * the rules of the Skylark language, throws EvalException in case of a semantical error.
+ * <p>Checks the semantics of the Expression using the {@link Environment} according to
+ * the rules of the Skylark language, throws {@link EvalException} in case of a semantical error.
*
* @see Statement
*/
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/FuncallExpression.java b/src/main/java/com/google/devtools/build/lib/syntax/FuncallExpression.java
index 8d1eb56..76737dd 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/FuncallExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/FuncallExpression.java
@@ -353,21 +353,11 @@
// TODO(bazel-team): If there's exactly one usable method, this works. If there are multiple
// matching methods, it still can be a problem. Figure out how the Java compiler does it
// exactly and copy that behaviour.
- // TODO(bazel-team): check if this and SkylarkBuiltInFunctions.createObject can be merged.
- private Object invokeJavaMethod(
- Object obj, Class<?> objClass, String methodName, List<Object> args, boolean hasKwArgs)
- throws EvalException {
+ private MethodDescriptor findJavaMethod(
+ Class<?> objClass, String methodName, List<Object> args) throws EvalException {
MethodDescriptor matchingMethod = null;
List<MethodDescriptor> methods = getMethods(objClass, methodName, args.size(), getLocation());
if (methods != null) {
- if (hasKwArgs) {
- throw new EvalException(
- func.getLocation(),
- String.format(
- "Keyword arguments are not allowed when calling a java method"
- + "\nwhile calling method '%s' on object of type %s",
- func.getName(), EvalUtils.getDataTypeNameFromClass(objClass)));
- }
for (MethodDescriptor method : methods) {
Class<?>[] params = method.getMethod().getParameterTypes();
int i = 0;
@@ -391,12 +381,11 @@
}
}
if (matchingMethod != null && !matchingMethod.getAnnotation().structField()) {
- return callMethod(matchingMethod, methodName, obj, args.toArray(), getLocation());
- } else {
- throw new EvalException(getLocation(), "No matching method found for "
- + formatMethod(methodName, args) + " in "
- + EvalUtils.getDataTypeNameFromClass(objClass));
+ return matchingMethod;
}
+ throw new EvalException(getLocation(), "No matching method found for "
+ + formatMethod(methodName, args) + " in "
+ + EvalUtils.getDataTypeNameFromClass(objClass));
}
private String formatMethod(String methodName, List<Object> args) {
@@ -490,20 +479,7 @@
@Override
Object eval(Environment env) throws EvalException, InterruptedException {
- // Adds the calling rule to the stack trace of the Environment if it is a BUILD environment.
- // There are two reasons for this:
- // a) When using aliases in load(), the rule class name in the BUILD file will differ from
- // the implementation name in the bzl file. Consequently, we need to store the calling name.
- // b) We need the location of the calling rule inside the BUILD file.
- boolean hasAddedElement =
- env.isSkylark() ? false : env.tryAddingStackTraceRoot(new StackTraceElement(func, args));
- try {
- return (obj != null) ? invokeObjectMethod(env) : invokeGlobalFunction(env);
- } finally {
- if (hasAddedElement) {
- env.removeStackTraceRoot();
- }
- }
+ return (obj != null) ? invokeObjectMethod(env) : invokeGlobalFunction(env);
}
/**
@@ -550,15 +526,28 @@
// When calling a Java method, the name is not in the Environment,
// so evaluating 'func' would fail.
evalArguments(posargs, kwargs, env, null);
+ Class<?> objClass;
+ Object obj;
if (objValue instanceof Class<?>) {
- // Static Java method call. We can return the value from here directly because
- // invokeJavaMethod() has special checks.
- return invokeJavaMethod(
- null, (Class<?>) objValue, func.getName(), posargs.build(), !kwargs.isEmpty());
+ // Static call
+ obj = null;
+ objClass = (Class<?>) objValue;
} else {
- return invokeJavaMethod(
- objValue, objValue.getClass(), func.getName(), posargs.build(), !kwargs.isEmpty());
+ obj = objValue;
+ objClass = objValue.getClass();
}
+ String name = func.getName();
+ ImmutableList<Object> args = posargs.build();
+ MethodDescriptor method = findJavaMethod(objClass, name, args);
+ if (!kwargs.isEmpty()) {
+ throw new EvalException(
+ func.getLocation(),
+ String.format(
+ "Keyword arguments are not allowed when calling a java method"
+ + "\nwhile calling method '%s' for type %s",
+ name, EvalUtils.getDataTypeNameFromClass(objClass)));
+ }
+ return callMethod(method, name, obj, args.toArray(), getLocation());
} else {
throw new EvalException(
getLocation(),
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/FunctionDefStatement.java b/src/main/java/com/google/devtools/build/lib/syntax/FunctionDefStatement.java
index ae7c027..acc09c9 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/FunctionDefStatement.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/FunctionDefStatement.java
@@ -50,10 +50,14 @@
defaultValues.add(expr.eval(env));
}
}
- env.update(ident.getName(), new UserDefinedFunction(
- ident, FunctionSignature.WithValues.<Object, SkylarkType>create(
- signature.getSignature(), defaultValues, types),
- statements, (SkylarkEnvironment) env));
+ env.update(
+ ident.getName(),
+ new UserDefinedFunction(
+ ident,
+ FunctionSignature.WithValues.<Object, SkylarkType>create(
+ signature.getSignature(), defaultValues, types),
+ statements,
+ env.getGlobals()));
}
@Override
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/LValue.java b/src/main/java/com/google/devtools/build/lib/syntax/LValue.java
index df5f486..1a39755 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/LValue.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/LValue.java
@@ -84,8 +84,7 @@
if (env.isSkylark()) {
// The variable may have been referenced successfully if a global variable
// with the same name exists. In this case an Exception needs to be thrown.
- SkylarkEnvironment skylarkEnv = (SkylarkEnvironment) env;
- if (skylarkEnv.hasBeenReadGlobalVariable(ident.getName())) {
+ if (env.isKnownGlobalVariable(ident.getName())) {
throw new EvalException(
loc,
String.format(
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/MethodLibrary.java b/src/main/java/com/google/devtools/build/lib/syntax/MethodLibrary.java
index 996ae41..b1ca1f6 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/MethodLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/MethodLibrary.java
@@ -776,7 +776,7 @@
new BuiltinFunction("append") {
public Runtime.NoneType invoke(List<Object> self, Object item,
Location loc, Environment env) throws EvalException, ConversionException {
- if (env.isSkylark()) {
+ if (env.isCallerSkylark()) {
throw new EvalException(loc,
"function 'append' is not available in Skylark");
}
@@ -806,7 +806,7 @@
new BuiltinFunction("extend") {
public Runtime.NoneType invoke(List<Object> self, List<Object> items,
Location loc, Environment env) throws EvalException, ConversionException {
- if (env.isSkylark()) {
+ if (env.isCallerSkylark()) {
throw new EvalException(loc,
"function 'append' is not available in Skylark");
}
@@ -920,7 +920,7 @@
List<Object> list = Lists.newArrayListWithCapacity(dict.size());
for (Map.Entry<?, ?> entries : dict.entrySet()) {
List<?> item = ImmutableList.of(entries.getKey(), entries.getValue());
- list.add(env.isSkylark() ? SkylarkList.tuple(item) : item);
+ list.add(env.isCallerSkylark() ? SkylarkList.tuple(item) : item);
}
return convert(list, env, loc);
}
@@ -966,7 +966,7 @@
@SuppressWarnings("unchecked")
private static Iterable<Object> convert(Collection<?> list, Environment env, Location loc)
throws EvalException {
- if (env.isSkylark()) {
+ if (env.isCallerSkylark()) {
return SkylarkList.list(list, loc);
} else {
return Lists.newArrayList(list);
@@ -1386,7 +1386,7 @@
useLocation = true, useEnvironment = true)
private static final BuiltinFunction print = new BuiltinFunction("print") {
public Runtime.NoneType invoke(String sep, SkylarkList starargs,
- Location loc, SkylarkEnvironment env) throws EvalException {
+ Location loc, Environment env) throws EvalException {
String msg = Joiner.on(sep).join(Iterables.transform(starargs,
new com.google.common.base.Function<Object, String>() {
@Override
@@ -1493,19 +1493,6 @@
/**
- * Set up a given environment for supported class methods.
- */
- public static void setupMethodEnvironment(Environment env) {
- setupMethodEnvironment(env, env.isSkylark() ? skylarkGlobalFunctions : buildGlobalFunctions);
- }
-
- private static void setupMethodEnvironment(Environment env, Iterable<BaseFunction> functions) {
- for (BaseFunction function : functions) {
- env.update(function.getName(), function);
- }
- }
-
- /**
* Collect global functions for the validation environment.
*/
public static void setupValidationEnvironment(Set<String> builtIn) {
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Mutability.java b/src/main/java/com/google/devtools/build/lib/syntax/Mutability.java
new file mode 100644
index 0000000..5120f8d
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Mutability.java
@@ -0,0 +1,136 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.syntax;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * A Mutability is a resource associated with an {@link Environment} during an evaluation,
+ * that gives those who possess it a revokable capability to mutate this Environment and
+ * the objects created within that {@link Environment}. At the end of the evaluation,
+ * the resource is irreversibly closed, at which point the capability is revoked,
+ * and it is not possible to mutate either this {@link Environment} or these objects.
+ *
+ * <p>Evaluation in an {@link Environment} may thus mutate objects created in the same
+ * {@link Environment}, but may not mutate {@link Freezable} objects (lists, sets, dicts)
+ * created in a previous, concurrent or future {@link Environment}, and conversely,
+ * the bindings and objects in this {@link Environment} will be protected from
+ * mutation by evaluation in a different {@link Environment}.
+ *
+ * <p>Only a single thread may use the {@link Environment} and objects created within it while the
+ * Mutability is still mutable as tested by {@link #isMutable}. Once the Mutability resource
+ * is closed, the {@link Environment} and its objects are immutable and can be simultaneously used
+ * by arbitrarily many threads.
+ *
+ * <p>The safe usage of a Mutability requires to always use try-with-resource style:
+ * <code>try(Mutability mutability = Mutability.create(fmt, ...)) { ... }</code>
+ * Thus, you can create a Mutability, build an {@link Environment}, mutate that {@link Environment}
+ * and create mutable objects as you evaluate in that {@link Environment}, and finally return the
+ * resulting {@link Environment}, at which point the resource is closed, and the {@link Environment}
+ * and the objects it contains all become immutable.
+ * (Unsafe usage is allowed only in test code that is not part of the Bazel jar.)
+ */
+// TODO(bazel-team): When we start using Java 8, this safe usage pattern can be enforced
+// through the use of a higher-order function.
+public final class Mutability implements AutoCloseable {
+ private boolean isMutable;
+ private final Object annotation; // For error reporting
+
+ /**
+ * Creates a Mutability.
+ * @param annotation an Object used for error reporting,
+ * describing to the user the context in which this Mutability was active.
+ */
+ private Mutability(Object annotation) {
+ this.isMutable = true;
+ this.annotation = Preconditions.checkNotNull(annotation);
+ }
+
+ /**
+ * Creates a Mutability.
+ * @param pattern is a {@link Printer#format} pattern used to lazily produce a string
+ * for error reporting
+ * @param arguments are the optional {@link Printer#format} arguments to produce that string
+ */
+ public static Mutability create(String pattern, Object... arguments) {
+ return new Mutability(Printer.formattable(pattern, arguments));
+ }
+
+ Object getAnnotation() {
+ return annotation;
+ }
+
+ @Override
+ public String toString() {
+ return String.format(isMutable ? "[%s]" : "(%s)", annotation);
+ }
+
+ boolean isMutable() {
+ return isMutable;
+ }
+
+ /**
+ * Freezes this Mutability, marking as immutable all {@link Freezable} objects that use it.
+ */
+ @Override
+ public void close() {
+ isMutable = false;
+ }
+
+ /**
+ * A MutabilityException will be thrown when the user attempts to mutate an object he shouldn't.
+ */
+ static class MutabilityException extends Exception {
+ MutabilityException(String message) {
+ super(message);
+ }
+ }
+
+ /**
+ * Each {@link Freezable} object possesses a revokable Mutability attribute telling whether
+ * the object is still mutable. All {@link Freezable} objects created in the same
+ * {@link Environment} will share the same Mutability, inherited from this {@link Environment}.
+ * Only evaluation in the same {@link Environment} is allowed to mutate these objects,
+ * and only until the Mutability is irreversibly revoked.
+ */
+ public interface Freezable {
+ /**
+ * Returns the {@link Mutability} capability associated with this Freezable object.
+ */
+ Mutability mutability();
+ }
+
+ /**
+ * Checks that this Freezable object can be mutated from the given {@link Environment}.
+ * @param object a Freezable object that we check is still mutable.
+ * @param env the {@link Environment} attempting the mutation.
+ * @throws MutabilityException when the object was frozen already, or is from another context.
+ */
+ public static void checkMutable(Freezable object, Environment env)
+ throws MutabilityException {
+ if (!object.mutability().isMutable()) {
+ throw new MutabilityException("trying to mutate a frozen object");
+ }
+ // Consider an {@link Environment} e1, in which is created {@link UserDefinedFunction} f1,
+ // that closes over some variable v1 bound to list l1. If somehow, via the magic of callbacks,
+ // f1 or l1 is passed as argument to some function f2 evaluated in {@link environment} e2
+ // while e1 is be mutable, e2, being a different {@link Environment}, should not be
+ // allowed to mutate objects from e1. It's a bug, that shouldn't happen in our current code
+ // base, so we throw an AssertionError. If in the future such situations are allowed to happen,
+ // then we should throw a MutabilityException instead.
+ if (!object.mutability().equals(env.mutability())) {
+ throw new AssertionError("trying to mutate an object from a different context");
+ }
+ }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Runtime.java b/src/main/java/com/google/devtools/build/lib/syntax/Runtime.java
index 50ef2546..9230d6b 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Runtime.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Runtime.java
@@ -33,11 +33,11 @@
@SkylarkSignature(name = "True", returnType = Boolean.class,
doc = "Literal for the boolean true.")
- static final Boolean TRUE = true;
+ private static final Boolean TRUE = true;
@SkylarkSignature(name = "False", returnType = Boolean.class,
doc = "Literal for the boolean false.")
- static final Boolean FALSE = false;
+ private static final Boolean FALSE = false;
/**
* There should be only one instance of this type to allow "== None" tests.
@@ -70,11 +70,11 @@
/**
* Set up a given environment for supported class methods.
*/
- static Environment setupConstants(Environment env) throws EvalException {
+ static Environment setupConstants(Environment env) {
// In Python 2.x, True and False are global values and can be redefined by the user.
// In Python 3.x, they are keywords. We implement them as values, for the sake of
// simplicity. We define them as Boolean objects.
- return env.update("False", FALSE).update("True", TRUE).update("None", NONE);
+ return env.setup("False", FALSE).setup("True", TRUE).setup("None", NONE);
}
@@ -128,7 +128,7 @@
public static void registerModuleGlobals(Environment env, Class<?> moduleClass) {
try {
if (moduleClass.isAnnotationPresent(SkylarkModule.class)) {
- env.update(
+ env.setup(
moduleClass.getAnnotation(SkylarkModule.class).name(), moduleClass.newInstance());
}
for (Field field : moduleClass.getDeclaredFields()) {
@@ -142,7 +142,7 @@
if (!(value instanceof BuiltinFunction.Factory
|| (value instanceof BaseFunction
&& !annotation.objectType().equals(Object.class)))) {
- env.update(annotation.name(), value);
+ env.setup(annotation.name(), value);
}
}
}
@@ -168,9 +168,9 @@
}
static void setupMethodEnvironment(
- Environment env, Iterable<BaseFunction> functions) throws EvalException {
+ Environment env, Iterable<BaseFunction> functions) {
for (BaseFunction function : functions) {
- env.update(function.getName(), function);
+ env.setup(function.getName(), function);
}
}
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
index 94b1917..6140acb 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
@@ -22,21 +22,25 @@
private final BaseFunction callback;
private final FuncallExpression ast;
- private final SkylarkEnvironment funcallEnv;
+ private final Environment funcallEnv;
- public SkylarkCallbackFunction(BaseFunction callback, FuncallExpression ast,
- SkylarkEnvironment funcallEnv) {
+ public SkylarkCallbackFunction(
+ BaseFunction callback, FuncallExpression ast, Environment funcallEnv) {
this.callback = callback;
this.ast = ast;
this.funcallEnv = funcallEnv;
}
public Object call(ClassObject ctx, Object... arguments) throws EvalException {
- try {
+ try (Mutability mutability = Mutability.create("callback %s", callback)) {
+ Environment env = Environment.builder(mutability)
+ .setSkylark()
+ .setEventHandler(funcallEnv.getEventHandler())
+ .setGlobals(funcallEnv.getGlobals())
+ .build();
return callback.call(
- ImmutableList.<Object>builder().add(ctx).add(arguments).build(), null, ast, funcallEnv);
- } catch (InterruptedException | ClassCastException
- | IllegalArgumentException e) {
+ ImmutableList.<Object>builder().add(ctx).add(arguments).build(), null, ast, env);
+ } catch (InterruptedException | ClassCastException | IllegalArgumentException e) {
throw new EvalException(ast.getLocation(), e.getMessage());
}
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java
deleted file mode 100644
index 0ff19f9..0000000
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java
+++ /dev/null
@@ -1,205 +0,0 @@
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-package com.google.devtools.build.lib.syntax;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
-import com.google.common.collect.Iterables;
-import com.google.devtools.build.lib.events.Event;
-import com.google.devtools.build.lib.events.EventHandler;
-import com.google.devtools.build.lib.util.Fingerprint;
-
-import java.io.Serializable;
-import java.util.Deque;
-import java.util.HashSet;
-import java.util.LinkedList;
-import java.util.Map.Entry;
-import java.util.Set;
-
-import javax.annotation.Nullable;
-
-/**
- * The environment for Skylark.
- */
-public class SkylarkEnvironment extends Environment implements Serializable {
-
- /**
- * This set contains the variable names of all the successful lookups from the global
- * environment. This is necessary because if in a function definition something
- * reads a global variable after which a local variable with the same name is assigned an
- * Exception needs to be thrown.
- */
- private final Set<String> readGlobalVariables = new HashSet<>();
-
- @Nullable private String fileContentHashCode;
-
- /**
- * Creates a Skylark Environment for function calling, from the global Environment of the
- * caller Environment (which must be a Skylark Environment).
- */
- public static SkylarkEnvironment createEnvironmentForFunctionCalling(
- Environment callerEnv, SkylarkEnvironment definitionEnv,
- UserDefinedFunction function) throws EvalException {
- if (callerEnv.stackTraceContains(function)) {
- throw new EvalException(
- function.getLocation(),
- "Recursion was detected when calling '" + function.getName() + "' from '"
- + Iterables.getLast(callerEnv.getStackTrace()).getName() + "'");
- }
- SkylarkEnvironment childEnv =
- // Always use the caller Environment's EventHandler. We cannot assume that the
- // definition Environment's EventHandler is still working properly.
- new SkylarkEnvironment(
- definitionEnv, callerEnv.getCopyOfStackTrace(), callerEnv.eventHandler);
- if (callerEnv.isLoadingPhase()) {
- childEnv.setLoadingPhase();
- }
-
- try {
- for (String varname : callerEnv.propagatingVariables) {
- childEnv.updateAndPropagate(varname, callerEnv.lookup(varname));
- }
- } catch (NoSuchVariableException e) {
- // This should never happen.
- throw new IllegalStateException(e);
- }
- return childEnv;
- }
-
- private SkylarkEnvironment(SkylarkEnvironment definitionEnv,
- Deque<StackTraceElement> stackTrace, EventHandler eventHandler) {
- super(definitionEnv.getGlobalEnvironment(), stackTrace);
- this.eventHandler = Preconditions.checkNotNull(eventHandler,
- "EventHandler cannot be null in an Environment which calls into Skylark");
- }
-
- /**
- * Creates a global SkylarkEnvironment.
- */
- public SkylarkEnvironment(EventHandler eventHandler, String astFileContentHashCode,
- Deque<StackTraceElement> stackTrace) {
- super(stackTrace);
- this.eventHandler = eventHandler;
- this.fileContentHashCode = astFileContentHashCode;
- }
-
- public SkylarkEnvironment(EventHandler eventHandler, String astFileContentHashCode) {
- this(eventHandler, astFileContentHashCode, new LinkedList<StackTraceElement>());
- }
-
- @VisibleForTesting
- public SkylarkEnvironment(EventHandler eventHandler) {
- this(eventHandler, null);
- }
-
- public SkylarkEnvironment(SkylarkEnvironment globalEnv) {
- super(globalEnv);
- this.eventHandler = globalEnv.eventHandler;
- }
-
- /**
- * Clones this Skylark global environment.
- */
- public SkylarkEnvironment cloneEnv(EventHandler eventHandler) {
- Preconditions.checkArgument(isGlobal());
- SkylarkEnvironment newEnv =
- new SkylarkEnvironment(eventHandler, this.fileContentHashCode, getCopyOfStackTrace());
- for (Entry<String, Object> entry : env.entrySet()) {
- newEnv.env.put(entry.getKey(), entry.getValue());
- }
- return newEnv;
- }
-
- /**
- * Returns the global environment. Only works for Skylark environments. For the global Skylark
- * environment this method returns this Environment.
- */
- public SkylarkEnvironment getGlobalEnvironment() {
- // If there's a parent that's the global environment, otherwise this is.
- return parent != null ? (SkylarkEnvironment) parent : this;
- }
-
- /**
- * Returns true if this is a Skylark global environment.
- */
- @Override
- public boolean isGlobal() {
- return parent == null;
- }
-
- /**
- * Returns true if varname has been read as a global variable.
- */
- public boolean hasBeenReadGlobalVariable(String varname) {
- return readGlobalVariables.contains(varname);
- }
-
- @Override
- public boolean isSkylark() {
- return true;
- }
-
- /**
- * @return the value from the environment whose name is "varname".
- * @throws NoSuchVariableException if the variable is not defined in the environment.
- */
- @Override
- public Object lookup(String varname) throws NoSuchVariableException {
- Object value = env.get(varname);
- if (value == null) {
- if (parent != null && parent.hasVariable(varname)) {
- readGlobalVariables.add(varname);
- return parent.lookup(varname);
- }
- throw new NoSuchVariableException(varname);
- }
- return value;
- }
-
- /**
- * Like <code>lookup(String)</code>, but instead of throwing an exception in
- * the case where "varname" is not defined, "defaultValue" is returned instead.
- */
- @Override
- public Object lookup(String varname, Object defaultValue) {
- throw new UnsupportedOperationException();
- }
-
- /**
- * Returns the class of the variable or null if the variable does not exist. This function
- * works only in the local Environment, it doesn't check the global Environment.
- */
- public Class<?> getVariableType(String varname) {
- Object variable = env.get(varname);
- return variable != null ? EvalUtils.getSkylarkType(variable.getClass()) : null;
- }
-
- public void handleEvent(Event event) {
- eventHandler.handle(event);
- }
-
- /**
- * Returns a hash code calculated from the hash code of this Environment and the
- * transitive closure of other Environments it loads.
- */
- public String getTransitiveFileContentHashCode() {
- Fingerprint fingerprint = new Fingerprint();
- fingerprint.addString(Preconditions.checkNotNull(fileContentHashCode));
- // Calculate a new hash from the hash of the loaded Environments.
- for (SkylarkEnvironment env : importedExtensions.values()) {
- fingerprint.addString(env.getTransitiveFileContentHashCode());
- }
- return fingerprint.hexDigestAndReset();
- }
-}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSignatureProcessor.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSignatureProcessor.java
index bf3c832..6b31625 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSignatureProcessor.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSignatureProcessor.java
@@ -204,8 +204,13 @@
} else if (param.defaultValue().isEmpty()) {
return Runtime.NONE;
} else {
- try {
- return EvaluationContext.SKYLARK_INITIALIZATION.evalExpression(param.defaultValue());
+ try (Mutability mutability = Mutability.create("initialization")) {
+ return Environment.builder(mutability)
+ .setSkylark()
+ .setGlobals(Environment.CONSTANTS_ONLY)
+ .setEventHandler(Environment.FAIL_FAST_HANDLER)
+ .build()
+ .eval(param.defaultValue());
} catch (Exception e) {
throw new RuntimeException(String.format(
"Exception while processing @SkylarkSignature.Param %s, default value %s",
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Statement.java b/src/main/java/com/google/devtools/build/lib/syntax/Statement.java
index ca89b1a..2c99209 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Statement.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Statement.java
@@ -27,8 +27,8 @@
abstract void exec(Environment env) throws EvalException, InterruptedException;
/**
- * Checks the semantics of the Statement using the SkylarkEnvironment according to
- * the rules of the Skylark language. The SkylarkEnvironment can be used e.g. to check
+ * Checks the semantics of the Statement using the Environment according to
+ * the rules of the Skylark language. The Environment can be used e.g. to check
* variable type collision, read only variables, detecting recursion, existence of
* built-in variables, functions, etc.
*
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/UserDefinedFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/UserDefinedFunction.java
index f50e6ee..537f29f 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/UserDefinedFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/UserDefinedFunction.java
@@ -14,6 +14,7 @@
package com.google.devtools.build.lib.syntax;
import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.events.Location.LineAndColumn;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.ProfilerTask;
@@ -26,15 +27,16 @@
public class UserDefinedFunction extends BaseFunction {
private final ImmutableList<Statement> statements;
- private final SkylarkEnvironment definitionEnv;
+
+ // we close over the globals at the time of definition
+ private final Environment.Frame definitionGlobals;
protected UserDefinedFunction(Identifier function,
FunctionSignature.WithValues<Object, SkylarkType> signature,
- ImmutableList<Statement> statements, SkylarkEnvironment definitionEnv) {
+ ImmutableList<Statement> statements, Environment.Frame definitionGlobals) {
super(function.getName(), signature, function.getLocation());
-
this.statements = statements;
- this.definitionEnv = definitionEnv;
+ this.definitionGlobals = definitionGlobals;
}
public FunctionSignature.WithValues<Object, SkylarkType> getFunctionSignature() {
@@ -48,23 +50,36 @@
@Override
public Object call(Object[] arguments, FuncallExpression ast, Environment env)
throws EvalException, InterruptedException {
- ImmutableList<String> names = signature.getSignature().getNames();
-
- // Registering the functions's arguments as variables in the local Environment
- int i = 0;
- for (String name : names) {
- env.update(name, arguments[i++]);
+ if (!env.mutability().isMutable()) {
+ throw new EvalException(getLocation(), "Trying to call in frozen environment");
+ }
+ if (env.getStackTrace().contains(this)) {
+ throw new EvalException(getLocation(),
+ String.format("Recursion was detected when calling '%s' from '%s'",
+ getName(), Iterables.getLast(env.getStackTrace()).getName()));
}
long startTimeProfiler = Profiler.nanoTimeMaybe();
Statement lastStatement = null;
try {
- for (Statement stmt : statements) {
- lastStatement = stmt;
- stmt.exec(env);
+ env.enterScope(this, ast, definitionGlobals);
+ ImmutableList<String> names = signature.getSignature().getNames();
+
+ // Registering the functions's arguments as variables in the local Environment
+ int i = 0;
+ for (String name : names) {
+ env.update(name, arguments[i++]);
}
- } catch (ReturnStatement.ReturnException e) {
- return e.getValue();
+
+ try {
+ for (Statement stmt : statements) {
+ lastStatement = stmt;
+ stmt.exec(env);
+ }
+ } catch (ReturnStatement.ReturnException e) {
+ return e.getValue();
+ }
+ return Runtime.NONE;
} catch (EvalExceptionWithStackTrace ex) {
// We need this block since the next "catch" must only catch EvalExceptions that don't have a
// stack trace yet.
@@ -79,8 +94,8 @@
startTimeProfiler,
ProfilerTask.SKYLARK_USER_FN,
getLocationPathAndLine() + "#" + getName());
+ env.exitScope();
}
- return Runtime.NONE;
}
/**
@@ -105,14 +120,4 @@
}
return builder.toString();
}
-
-
- /**
- * Creates a new environment for the execution of this function.
- */
- @Override
- protected Environment getOrCreateChildEnvironment(Environment parent) throws EvalException {
- return SkylarkEnvironment.createEnvironmentForFunctionCalling(
- parent, definitionEnv, this);
- }
}
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java b/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
index 9b71f96..9d56271 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
@@ -15,7 +15,6 @@
package com.google.devtools.build.lib.syntax;
import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.events.Location;
import java.util.HashMap;
@@ -31,7 +30,7 @@
* @see Statement#validate
* @see Expression#validate
*/
-public class ValidationEnvironment {
+public final class ValidationEnvironment {
private final ValidationEnvironment parent;
@@ -45,9 +44,6 @@
// branches of if-else statements.
private Stack<Set<String>> futureReadOnlyVariables = new Stack<>();
- // Whether this validation environment is not modified therefore clonable or not.
- private boolean clonable;
-
/**
* Tracks the number of nested for loops that contain the statement that is currently being
* validated
@@ -55,38 +51,14 @@
private int loopCount = 0;
/**
- * Create a ValidationEnvironment for a given global Environment
+ * Create a ValidationEnvironment for a given global Environment.
*/
public ValidationEnvironment(Environment env) {
- this(env.getVariableNames());
Preconditions.checkArgument(env.isGlobal());
- }
-
- public ValidationEnvironment(Set<String> builtinVariables) {
parent = null;
+ Set<String> builtinVariables = env.getVariableNames();
variables.addAll(builtinVariables);
readOnlyVariables.addAll(builtinVariables);
- clonable = true;
- }
-
- private ValidationEnvironment(Set<String> builtinVariables, Set<String> readOnlyVariables) {
- parent = null;
- this.variables = new HashSet<>(builtinVariables);
- this.readOnlyVariables = new HashSet<>(readOnlyVariables);
- clonable = false;
- }
-
- // ValidationEnvironment for a new Environment()
- private static ImmutableSet<String> globalTypes = ImmutableSet.of("False", "True", "None");
-
- public ValidationEnvironment() {
- this(globalTypes);
- }
-
- @Override
- public ValidationEnvironment clone() {
- Preconditions.checkState(clonable);
- return new ValidationEnvironment(variables, readOnlyVariables);
}
/**
@@ -95,7 +67,6 @@
public ValidationEnvironment(ValidationEnvironment parent) {
// Don't copy readOnlyVariables: Variables may shadow global values.
this.parent = parent;
- this.clonable = false;
}
/**
@@ -120,7 +91,6 @@
}
variables.add(varname);
variableLocations.put(varname, location);
- clonable = false;
}
private void checkReadonly(String varname, Location location) throws EvalException {
@@ -133,7 +103,8 @@
* Returns true if the symbol exists in the validation environment.
*/
public boolean hasSymbolInEnvironment(String varname) {
- return variables.contains(varname) || topLevel().variables.contains(varname);
+ return variables.contains(varname)
+ || (parent != null && topLevel().variables.contains(varname));
}
private ValidationEnvironment topLevel() {
@@ -147,7 +118,6 @@
*/
public void startTemporarilyDisableReadonlyCheckSession() {
futureReadOnlyVariables.add(new HashSet<String>());
- clonable = false;
}
/**
@@ -159,7 +129,6 @@
if (!futureReadOnlyVariables.isEmpty()) {
futureReadOnlyVariables.peek().addAll(variables);
}
- clonable = false;
}
/**
@@ -167,7 +136,6 @@
*/
public void finishTemporarilyDisableReadonlyCheckBranch() {
readOnlyVariables.removeAll(futureReadOnlyVariables.peek());
- clonable = false;
}
/**
