Skylark: SlicingExpression: do not create new nodes for optional expressions
RELNOTES: None.
PiperOrigin-RevId: 185353994
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SliceExpression.java b/src/main/java/com/google/devtools/build/lib/syntax/SliceExpression.java
index a2b6036..54c194a 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SliceExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SliceExpression.java
@@ -16,14 +16,15 @@
import com.google.devtools.build.lib.events.Location;
import java.io.IOException;
import java.util.List;
+import javax.annotation.Nullable;
/** Syntax node for a slice expression, e.g. obj[:len(obj):2]. */
public final class SliceExpression extends Expression {
private final Expression object;
- private final Expression start;
- private final Expression end;
- private final Expression step;
+ @Nullable private final Expression start;
+ @Nullable private final Expression end;
+ @Nullable private final Expression step;
public SliceExpression(Expression object, Expression start, Expression end, Expression step) {
this.object = object;
@@ -36,43 +37,32 @@
return object;
}
- public Expression getStart() {
+ public @Nullable Expression getStart() {
return start;
}
- public Expression getEnd() {
+ public @Nullable Expression getEnd() {
return end;
}
- public Expression getStep() {
+ public @Nullable Expression getStep() {
return step;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
- boolean startIsDefault =
- (start instanceof Identifier) && ((Identifier) start).getName().equals("None");
- boolean endIsDefault =
- (end instanceof Identifier) && ((Identifier) end).getName().equals("None");
- boolean stepIsDefault =
- (step instanceof IntegerLiteral) && ((IntegerLiteral) step).getValue() == 1;
-
object.prettyPrint(buffer);
buffer.append('[');
- // Start and end are omitted if they are the literal identifier None, which is the default value
- // inserted by the parser if no bound is given. Likewise, step is omitted if it is the literal
- // integer 1.
- //
// The first separator colon is unconditional. The second separator appears only if step is
// printed.
- if (!startIsDefault) {
+ if (start != null) {
start.prettyPrint(buffer);
}
buffer.append(':');
- if (!endIsDefault) {
+ if (end != null) {
end.prettyPrint(buffer);
}
- if (!stepIsDefault) {
+ if (step != null) {
buffer.append(':');
step.prettyPrint(buffer);
}
@@ -82,9 +72,9 @@
@Override
Object doEval(Environment env) throws EvalException, InterruptedException {
Object objValue = object.eval(env);
- Object startValue = start.eval(env);
- Object endValue = end.eval(env);
- Object stepValue = step.eval(env);
+ Object startValue = start == null ? Runtime.NONE : start.eval(env);
+ Object endValue = end == null ? Runtime.NONE : end.eval(env);
+ Object stepValue = step == null ? Runtime.NONE : step.eval(env);
Location loc = getLocation();
if (objValue instanceof SkylarkList) {
