1 files changed, 97 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/ForStatement.java b/src/main/java/com/google/devtools/build/lib/syntax/ForStatement.java
new file mode 100644
index 0000000000..34a4eea416
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/ForStatement.java
@@ -0,0 +1,97 @@
+// 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.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+
+/**
+ * Syntax node for a for loop statement.
+ */
+public final class ForStatement extends Statement {
+
+  private final Ident variable;
+  private final Expression collection;
+  private final ImmutableList<Statement> block;
+
+  /**
+   * Constructs a for loop statement.
+   */
+  ForStatement(Ident variable, Expression collection, List<Statement> block) {
+    this.variable = Preconditions.checkNotNull(variable);
+    this.collection = Preconditions.checkNotNull(collection);
+    this.block = ImmutableList.copyOf(block);
+  }
+
+  public Ident getVariable() {
+    return variable;
+  }
+
+  public Expression getCollection() {
+    return collection;
+  }
+
+  public ImmutableList<Statement> block() {
+    return block;
+  }
+
+  @Override
+  public String toString() {
+    // TODO(bazel-team): if we want to print the complete statement, the function
+    // needs an extra argument to specify indentation level.
+    return "for " + variable + " in " + collection + ": ...\n";
+  }
+
+  @Override
+  void exec(Environment env) throws EvalException, InterruptedException {
+    Object o = collection.eval(env);
+    Iterable<?> col = EvalUtils.toIterable(o, getLocation());
+
+    int i = 0;
+    for (Object it : ImmutableList.copyOf(col)) {
+      env.update(variable.getName(), it);
+      for (Statement stmt : block) {
+        stmt.exec(env);
+      }
+      i++;
+    }
+    // TODO(bazel-team): This should not happen if every collection is immutable.
+    if (i != EvalUtils.size(col)) {
+      throw new EvalException(getLocation(),
+          String.format("Cannot modify '%s' during during iteration.", collection.toString()));
+    }
+  }
+
+  @Override
+  public void accept(SyntaxTreeVisitor visitor) {
+    visitor.visit(this);
+  }
+
+  @Override
+  void validate(ValidationEnvironment env) throws EvalException {
+    if (env.isTopLevel()) {
+      throw new EvalException(getLocation(),
+          "'For' is not allowed as a the top level statement");
+    }
+    // TODO(bazel-team): validate variable. Maybe make it temporarily readonly.
+    SkylarkType type = collection.validate(env);
+    env.checkIterable(type, getLocation());
+    env.update(variable.getName(), SkylarkType.UNKNOWN, getLocation());
+    for (Statement stmt : block) {
+      stmt.validate(env);
+    }
+  }
+}