Add initial prototype for the GN meta-buildsystem.

tools/gn/function_toolchain.cc

Index: tools/gn/function_toolchain.cc
diff --git a/tools/gn/function_toolchain.cc b/tools/gn/function_toolchain.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b78c639aca2c2b7cbceac4ca6b60986ba10c6255
--- /dev/null
+++ b/tools/gn/function_toolchain.cc
@@ -0,0 +1,126 @@
+// Copyright (c) 2013 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/err.h"
+#include "tools/gn/functions.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/toolchain.h"
+
+namespace {
+
+// This is jsut a unique value to take the address of to use as the key for
+// the toolchain property on a scope.
+const int kToolchainPropertyKey = 0;
+
+// Reads the given string from the scope (if present) and puts the result into
+// dest. If the value is not a string, sets the error and returns false.
+bool ReadString(Scope& scope, const char* var, std::string* dest, Err* err) {
+  const Value* v = scope.GetValue(var, true);
+  if (!v)
+    return true;  // Not present is fine.
+
+  if (!v->VerifyTypeIs(Value::STRING, err))
+    return false;
+  *dest = v->string_value();
+  return true;
+}
+
+}  // namespace
+
+Value ExecuteToolchain(Scope* scope,
+                       const FunctionCallNode* function,
+                       const std::vector<Value>& args,
+                       BlockNode* block,
+                       Err* err) {
+  if (!EnsureNotProcessingImport(function, scope, err) ||
+      !EnsureNotProcessingBuildConfig(function, scope, err))
+    return Value();
+
+  // Note that we don't want to use MakeLabelForScope since that will include
+  // the toolchain name in the label, and toolchain labels don't themselves
+  // have toolchain names.
+  const SourceDir& input_dir = SourceDirForFunctionCall(function);
+  Label label(input_dir, args[0].string_value(), SourceDir(), std::string());
+  if (g_scheduler->verbose_logging())
+    g_scheduler->Log("Generating toolchain", label.GetUserVisibleName(true));
+
+  // This object will actually be copied into the one owned by the toolchain
+  // manager, but that has to be done in the lock.
+  Toolchain toolchain(label);
+
+  Scope block_scope(scope);
+  block_scope.SetProperty(&kToolchainPropertyKey, &toolchain);
+  block->ExecuteBlockInScope(&block_scope, err);
+  block_scope.SetProperty(&kToolchainPropertyKey, NULL);
+  if (err->has_error())
+    return Value();
+  if (!block_scope.CheckForUnusedVars(err))
+    return Value();
+
+  const BuildSettings* build_settings = scope->settings()->build_settings();
+  {
+    // Save the toolchain definition in the toolchain manager and mark the
+    // corresponding item in the dependency tree resolved so that targets
+    // that depend on this toolchain know it's ready.
+    base::AutoLock lock(build_settings->item_tree().lock());
+    build_settings->toolchain_manager().SetToolchainDefinitionLocked(
+        toolchain, function->GetRange(), err);
+    build_settings->item_tree().MarkItemGeneratedLocked(label);
+  }
+  return Value();
+}
+
+Value ExecuteTool(Scope* scope,
+                  const FunctionCallNode* function,
+                  const std::vector<Value>& args,
+                  BlockNode* block,
+                  Err* err) {
+  // Find the toolchain definition we're executing inside of. The toolchain
+  // function will set a property pointing to it that we'll pick up.
+  Toolchain* toolchain = reinterpret_cast<Toolchain*>(
+      scope->GetProperty(&kToolchainPropertyKey, NULL));
+  if (!toolchain) {
+    *err = Err(function->function(), "tool() called outside of toolchain().",
+        "The tool() function can only be used inside a toolchain() "
+        "definition.");
+    return Value();
+  }
+
+  if (!EnsureSingleStringArg(function, args, err))
+    return Value();
+  const std::string& tool_name = args[0].string_value();
+  Toolchain::ToolType tool_type = Toolchain::ToolNameToType(tool_name);
+  if (tool_type == Toolchain::TYPE_NONE) {
+    *err = Err(args[0], "Unknown tool type");
+    return Value();
+  }
+
+  // Run the tool block.
+  Scope block_scope(scope);
+  block->ExecuteBlockInScope(&block_scope, err);
+  if (err->has_error())
+    return Value();
+
+  // Extract the stuff we need.
+  Toolchain::Tool t;
+  if (!ReadString(block_scope, "command", &t.command, err) ||
+      !ReadString(block_scope, "depfile", &t.depfile, err) ||
+      !ReadString(block_scope, "deps", &t.deps, err) ||
+      !ReadString(block_scope, "description", &t.description, err) ||
+      !ReadString(block_scope, "pool", &t.pool, err) ||
+      !ReadString(block_scope, "restat", &t.restat, err) ||
+      !ReadString(block_scope, "rspfile", &t.rspfile, err) ||
+      !ReadString(block_scope, "rspfile_content", &t.rspfile_content, err))
+    return Value();
+
+  // Make sure there weren't any vars set in this tool that were unused.
+  if (!block_scope.CheckForUnusedVars(err))
+    return Value();
+
+  toolchain->SetTool(tool_type, t);
+  return Value();
+}