Skylark: Allow list slices
--
MOS_MIGRATED_REVID=88727892
diff --git a/src/main/java/com/google/devtools/build/lib/packages/MethodLibrary.java b/src/main/java/com/google/devtools/build/lib/packages/MethodLibrary.java
index 8035d08..bee5ca1 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/MethodLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/MethodLibrary.java
@@ -67,18 +67,18 @@
// Convert string index in the same way Python does.
// If index is negative, starts from the end.
// If index is outside bounds, it is restricted to the valid range.
- private static int getPythonStringIndex(int index, int stringLength) {
+ private static int getClampedIndex(int index, int length) {
if (index < 0) {
- index += stringLength;
+ index += length;
}
- return Math.max(Math.min(index, stringLength), 0);
+ return Math.max(Math.min(index, length), 0);
}
// Emulate Python substring function
// It converts out of range indices, and never fails
private static String getPythonSubstring(String str, int start, int end) {
- start = getPythonStringIndex(start, str.length());
- end = getPythonStringIndex(end, str.length());
+ start = getClampedIndex(start, str.length());
+ end = getClampedIndex(end, str.length());
if (start > end) {
return "";
} else {
@@ -225,7 +225,7 @@
end = Type.INTEGER.convert(args[3], "'rfind' argument");
}
int subpos = getPythonSubstring(thiz, start, end).lastIndexOf(sub);
- start = getPythonStringIndex(start, thiz.length());
+ start = getClampedIndex(start, thiz.length());
return subpos < 0 ? subpos : subpos + start;
}
};
@@ -256,7 +256,7 @@
end = Type.INTEGER.convert(args[3], "'find' argument");
}
int subpos = getPythonSubstring(thiz, start, end).indexOf(sub);
- start = getPythonStringIndex(start, thiz.length());
+ start = getClampedIndex(start, thiz.length());
return subpos < 0 ? subpos : subpos + start;
}
};
@@ -369,17 +369,33 @@
}
};
- // substring operator
- @SkylarkBuiltin(name = "$substring", hidden = true,
- doc = "String[<code>start</code>:<code>end</code>] returns a substring.")
- private static Function substring = new MixedModeFunction("$substring",
+ // slice operator
+ @SkylarkBuiltin(name = "$slice", hidden = true,
+ doc = "x[<code>start</code>:<code>end</code>] returns a slice or a list slice.")
+ private static Function slice = new MixedModeFunction("$slice",
ImmutableList.of("this", "start", "end"), 3, false) {
@Override
- public Object call(Object[] args, FuncallExpression ast) throws ConversionException {
- String thiz = Type.STRING.convert(args[0], "substring operand");
- int left = Type.INTEGER.convert(args[1], "substring operand");
- int right = Type.INTEGER.convert(args[2], "substring operand");
- return getPythonSubstring(thiz, left, right);
+ public Object call(Object[] args, FuncallExpression ast, Environment env)
+ throws EvalException, ConversionException {
+ int left = Type.INTEGER.convert(args[1], "start operand");
+ int right = Type.INTEGER.convert(args[2], "end operand");
+
+ // Substring
+ if (args[0] instanceof String) {
+ String thiz = Type.STRING.convert(args[0], "substring operand");
+ return getPythonSubstring(thiz, left, right);
+ }
+
+ // List slice
+ List<Object> list = Type.OBJECT_LIST.convert(args[0], "list operand");
+ left = getClampedIndex(left, list.size());
+ right = getClampedIndex(right, list.size());
+
+ List<Object> result = Lists.newArrayList();
+ for (int i = left; i < right; i++) {
+ result.add(list.get(i));
+ }
+ return convert(result, env, ast.getLocation());
}
};
@@ -500,6 +516,7 @@
}
};
+ // TODO(bazel-team): Use the same type for both Skylark and BUILD files.
@SuppressWarnings("unchecked")
private static Iterable<Object> convert(Collection<?> list, Environment env, Location loc)
throws EvalException {
@@ -937,10 +954,15 @@
.put(endswith, SkylarkType.BOOL)
.put(startswith, SkylarkType.BOOL)
.put(strip, SkylarkType.STRING)
- .put(substring, SkylarkType.STRING)
+ .put(slice, SkylarkType.STRING)
.put(count, SkylarkType.INT)
.build();
+ public static final Map<Function, SkylarkType> listPureFunctions = ImmutableMap
+ .<Function, SkylarkType>builder()
+ .put(slice, SkylarkType.LIST)
+ .build();
+
public static final List<Function> listFunctions = ImmutableList.of(append, extend);
public static final Map<Function, SkylarkType> dictFunctions = ImmutableMap
@@ -986,6 +1008,7 @@
setupMethodEnvironment(env, Map.class, dictFunctions.keySet());
env.registerFunction(String.class, index.getName(), index);
setupMethodEnvironment(env, String.class, stringFunctions.keySet());
+ setupMethodEnvironment(env, List.class, listPureFunctions.keySet());
if (env.isSkylarkEnabled()) {
env.registerFunction(SkylarkList.class, index.getName(), index);
setupMethodEnvironment(env, skylarkGlobalFunctions.keySet());
@@ -1033,5 +1056,9 @@
Map<String, SkylarkType> string = new HashMap<>();
setupValidationEnvironment(stringFunctions, string);
builtIn.put(SkylarkType.STRING, string);
+
+ Map<String, SkylarkType> list = new HashMap<>();
+ setupValidationEnvironment(listPureFunctions, string);
+ builtIn.put(SkylarkType.LIST, list);
}
}
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 c31d434..41fe332 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
@@ -247,7 +247,7 @@
@Override
public String toString() {
- if (func.getName().equals("$substring")) {
+ if (func.getName().equals("$slice")) {
return obj + "[" + args.get(0) + ":" + args.get(1) + "]";
}
if (func.getName().equals("$index")) {
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
index 45eae4c..68a4425 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
@@ -697,7 +697,7 @@
return makeFuncallExpression(receiver, new Ident("$index"), args,
start, token.right);
}
- // This is a substring
+ // This is a slice (or substring)
expect(TokenKind.COLON);
int loc2 = token.left;
if (token.kind == TokenKind.RBRACKET) {
@@ -708,7 +708,7 @@
expect(TokenKind.RBRACKET);
args.add(setLocation(new Argument.Positional(endExpr), loc2, endExpr));
- return makeFuncallExpression(receiver, new Ident("$substring"), args,
+ return makeFuncallExpression(receiver, new Ident("$slice"), args,
start, token.right);
}
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java b/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
index 0e69eff..e08f6d4 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
@@ -214,7 +214,7 @@
@Test
public void testSubstring() throws Exception {
FuncallExpression e = (FuncallExpression) parseExpr("'FOO.CC'[:].lower()[1:]");
- assertEquals("$substring", e.getFunction().getName());
+ assertEquals("$slice", e.getFunction().getName());
assertThat(e.getArguments()).hasSize(2);
e = (FuncallExpression) parseExpr("'FOO.CC'.lower()[1:].startswith('oo')");
@@ -222,7 +222,7 @@
assertThat(e.getArguments()).hasSize(1);
e = (FuncallExpression) parseExpr("'FOO.CC'[1:][:2]");
- assertEquals("$substring", e.getFunction().getName());
+ assertEquals("$slice", e.getFunction().getName());
assertThat(e.getArguments()).hasSize(2);
}
