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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "tools/gn/template.h"
#include "tools/gn/err.h"
#include "tools/gn/functions.h"
#include "tools/gn/parse_tree.h"
#include "tools/gn/scope.h"
#include "tools/gn/scope_per_file_provider.h"
#include "tools/gn/value.h"
Template::Template(const Scope* scope, const FunctionCallNode* def)
: closure_(scope->MakeClosure()),
definition_(def) {
Template::Template(scoped_ptr<Scope> scope, const FunctionCallNode* def)
: closure_(scope.Pass()),
definition_(def) {
Template::~Template() {
Value Template::Invoke(Scope* scope,
const FunctionCallNode* invocation,
const std::vector<Value>& args,
BlockNode* block,
Err* err) const {
// Don't allow templates to be executed from imported files. Imports are for
// simple values only.
if (!EnsureNotProcessingImport(invocation, scope, err))
return Value();
// First run the invocation's block. Need to allocate the scope on the heap
// so we can pass ownership to the template.
scoped_ptr<Scope> invocation_scope(new Scope(scope));
if (!FillTargetBlockScope(scope, invocation,
block, args, invocation_scope.get(), err))
return Value();
block->ExecuteBlockInScope(invocation_scope.get(), err);
if (err->has_error())
return Value();
// Set up the scope to run the template and set the current directory for the
// template (which ScopePerFileProvider uses to base the target-related
// variables target_gen_dir and target_out_dir on) to be that of the invoker.
// This way, files don't have to be rebased and target_*_dir works the way
// people expect (otherwise its to easy to be putting generated files in the
// gen dir corresponding to an imported file).
Scope template_scope(closure_.get());
ScopePerFileProvider per_file_provider(&template_scope, true);
// Targets defined in the template go in the collector for the invoking file.
// We jump through some hoops to avoid copying the invocation scope when
// setting it in the template scope (since the invocation scope may have
// large lists of source files in it and could be expensive to copy).
// Scope.SetValue will copy the value which will in turn copy the scope, but
// if we instead create a value and then set the scope on it, the copy can
// be avoided.
const char kInvoker[] = "invoker";
template_scope.SetValue(kInvoker, Value(NULL, scoped_ptr<Scope>()),
Value* invoker_value = template_scope.GetMutableValue(kInvoker, false);
const base::StringPiece target_name("target_name");
Value(invocation, args[0].string_value()),
// Actually run the template code.
Value result =
definition_->block()->ExecuteBlockInScope(&template_scope, err);
if (err->has_error())
return Value();
// Check for unused variables in the invocation scope. This will find typos
// of things the caller meant to pass to the template but the template didn't
// read out.
// This is a bit tricky because it's theoretically possible for the template
// to overwrite the value of "invoker" and free the Scope owned by the
// value. So we need to look it up again and don't do anything if it doesn't
// exist.
invoker_value = template_scope.GetMutableValue(kInvoker, false);
if (invoker_value && invoker_value->type() == Value::SCOPE) {
if (!invoker_value->scope_value()->CheckForUnusedVars(err))
return Value();
// Check for unused variables in the template itself.
if (!template_scope.CheckForUnusedVars(err))
return Value();
return result;
LocationRange Template::GetDefinitionRange() const {
return definition_->GetRange();