Add initial prototype for the GN meta-buildsystem.

tools/gn/scope.cc

Index: tools/gn/scope.cc
diff --git a/tools/gn/scope.cc b/tools/gn/scope.cc
new file mode 100644
index 0000000000000000000000000000000000000000..72664d7cc425c9d5a815cf3d0c916bb69de7aff3
--- /dev/null
+++ b/tools/gn/scope.cc
@@ -0,0 +1,372 @@
+// 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/scope.h"
+
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "tools/gn/parse_tree.h"
+
+namespace {
+
+// FLags set in the mode_flags_ of a scope. If a bit is set, it applies
+// recursively to all dependent scopes.
+const unsigned kProcessingBuildConfigFlag = 1;
+const unsigned kProcessingDefaultBuildConfigFlag = 2;
+const unsigned kProcessingImportFlag = 4;
+
+}  // namespace
+
+Scope::Scope(const Settings* settings)
+    : const_containing_(NULL),
+      mutable_containing_(NULL),
+      settings_(settings),
+      mode_flags_(0) {
+}
+
+Scope::Scope(Scope* parent)
+    : const_containing_(NULL),
+      mutable_containing_(parent),
+      settings_(parent->settings()),
+      mode_flags_(0) {
+}
+
+Scope::Scope(const Scope* parent)
+    : const_containing_(parent),
+      mutable_containing_(NULL),
+      settings_(parent->settings()),
+      mode_flags_(0) {
+}
+
+Scope::~Scope() {
+  STLDeleteContainerPairSecondPointers(target_defaults_.begin(),
+                                       target_defaults_.end());
+}
+
+const Value* Scope::GetValue(const base::StringPiece& ident,
+                             bool counts_as_used) {
+  // First check for programatically-provided values.
+  for (ProviderSet::const_iterator i = programmatic_providers_.begin();
+       i != programmatic_providers_.end(); ++i) {
+    const Value* v = (*i)->GetProgrammaticValue(ident);
+    if (v)
+      return v;
+  }
+
+  RecordMap::iterator found = values_.find(ident);
+  if (found != values_.end()) {
+    if (counts_as_used)
+      found->second.used = true;
+    return &found->second.value;
+  }
+
+  // Search in the parent scope.
+  if (const_containing_)
+    return const_containing_->GetValue(ident);
+  if (mutable_containing_)
+    return mutable_containing_->GetValue(ident, counts_as_used);
+  return NULL;
+}
+
+Value* Scope::GetValueForcedToCurrentScope(const base::StringPiece& ident,
+                                           const ParseNode* set_node) {
+  RecordMap::iterator found = values_.find(ident);
+  if (found != values_.end())
+    return &found->second.value;  // Already have in the current scope.
+
+  // Search in the parent scope.
+  if (containing()) {
+    const Value* in_containing = containing()->GetValue(ident);
+    if (in_containing) {
+      // Promote to current scope.
+      return SetValue(ident, *in_containing, set_node);
+    }
+  }
+  return NULL;
+}
+
+const Value* Scope::GetValue(const base::StringPiece& ident) const {
+  RecordMap::const_iterator found = values_.find(ident);
+  if (found != values_.end())
+    return &found->second.value;
+  if (containing())
+    return containing()->GetValue(ident);
+  return NULL;
+}
+
+Value* Scope::SetValue(const base::StringPiece& ident,
+                       const Value& v,
+                       const ParseNode* set_node) {
+  Record& r = values_[ident];  // Clears any existing value.
+  r.value = v;
+  r.value.set_origin(set_node);
+  return &r.value;
+}
+
+bool Scope::AddTemplate(const std::string& name, const FunctionCallNode* decl) {
+  if (GetTemplate(name))
+    return false;
+  templates_[name] = decl;
+  return true;
+}
+
+const FunctionCallNode* Scope::GetTemplate(const std::string& name) const {
+  TemplateMap::const_iterator found = templates_.find(name);
+  if (found != templates_.end())
+    return found->second;
+  if (containing())
+    return containing()->GetTemplate(name);
+  return NULL;
+}
+
+void Scope::MarkUsed(const base::StringPiece& ident) {
+  RecordMap::iterator found = values_.find(ident);
+  if (found == values_.end()) {
+    NOTREACHED();
+    return;
+  }
+  found->second.used = true;
+}
+
+void Scope::MarkUnused(const base::StringPiece& ident) {
+  RecordMap::iterator found = values_.find(ident);
+  if (found == values_.end()) {
+    NOTREACHED();
+    return;
+  }
+  found->second.used = false;
+}
+
+bool Scope::IsSetButUnused(const base::StringPiece& ident) const {
+  RecordMap::const_iterator found = values_.find(ident);
+  if (found != values_.end()) {
+    if (!found->second.used) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Scope::CheckForUnusedVars(Err* err) const {
+  for (RecordMap::const_iterator i = values_.begin();
+       i != values_.end(); ++i) {
+    if (!i->second.used) {
+      std::string help = "You set the variable \"" + i->first.as_string() +
+          "\" here and it was unused before it went\nout of scope.";
+
+      const BinaryOpNode* binary = i->second.value.origin()->AsBinaryOp();
+      if (binary) {
+        // Make a nicer error message for normal var sets.
+        *err = Err(binary->left()->GetRange(), "Assignment had no effect.",
+                   help);
+      } else {
+        // This will happen for internally-generated variables.
+        *err = Err(i->second.value.origin(), "Assignment had no effect.", help);
+      }
+      return false;
+    }
+  }
+  return true;
+}
+
+void Scope::GetCurrentScopeValues(KeyValueVector* output) const {
+  output->reserve(values_.size());
+  for (RecordMap::const_iterator i = values_.begin(); i != values_.end(); ++i) {
+    output->push_back(std::make_pair(i->first, i->second.value));
+  }
+}
+
+bool Scope::NonRecursiveMergeTo(Scope* dest,
+                                const ParseNode* node_for_err,
+                                const char* desc_for_err,
+                                Err* err) const {
+  // Values.
+  for (RecordMap::const_iterator i = values_.begin(); i != values_.end(); ++i) {
+    const Value* existing_value = dest->GetValue(i->first);
+    if (existing_value) {
+      // Value present in both the source and the dest.
+      std::string desc_string(desc_for_err);
+      *err = Err(node_for_err, "Value collision.",
+          "This " + desc_string + " contains \"" + i->first.as_string() + "\"");
+      err->AppendSubErr(Err(i->second.value, "defined here.",
+          "Which would clobber the one in your current scope"));
+      err->AppendSubErr(Err(*existing_value, "defined here.",
+          "Executing " + desc_string + " should not conflict with anything "
+          "in the current\nscope."));
+      return false;
+    }
+    dest->values_[i->first] = i->second;
+  }
+
+  // Target defaults are owning pointers.
+  for (NamedScopeMap::const_iterator i = target_defaults_.begin();
+       i != target_defaults_.end(); ++i) {
+    if (dest->GetTargetDefaults(i->first)) {
+      // TODO(brettw) it would be nice to know the origin of a
+      // set_target_defaults so we can give locations for the colliding target
+      // defaults.
+      std::string desc_string(desc_for_err);
+      *err = Err(node_for_err, "Target defaults collision.",
+          "This " + desc_string + " contains target defaults for\n"
+          "\"" + i->first + "\" which would clobber one for the\n"
+          "same target type in your current scope. It's unfortunate that I'm "
+          "too stupid\nto tell you the location of where the target defaults "
+          "were set. Usually\nthis happens in the BUILDCONFIG.gn file.");
+      return false;
+    }
+
+    Scope* s = new Scope(settings_);
+    i->second->NonRecursiveMergeTo(s, node_for_err, "<SHOULDN'T HAPPEN>", err);
+    dest->target_defaults_[i->first] = s;
+  }
+
+  // Sources assignment filter.
+  if (sources_assignment_filter_) {
+    if (dest->GetSourcesAssignmentFilter()) {
+      // Sources assignment filter present in both the source and the dest.
+      std::string desc_string(desc_for_err);
+      *err = Err(node_for_err, "Assignment filter collision.",
+          "The " + desc_string + " contains a sources_assignment_filter which\n"
+          "would clobber the one in your current scope.");
+      return false;
+    }
+    dest->sources_assignment_filter_.reset(
+        new PatternList(*sources_assignment_filter_));
+  }
+
+  // Templates.
+  for (TemplateMap::const_iterator i = templates_.begin();
+       i != templates_.end(); ++i) {
+    const FunctionCallNode* existing_template = dest->GetTemplate(i->first);
+    if (existing_template) {
+      // Rule present in both the source and the dest.
+      std::string desc_string(desc_for_err);
+      *err = Err(node_for_err, "Template collision.",
+          "This " + desc_string + " contains a template \"" + i->first + "\"");
+      err->AppendSubErr(Err(i->second->function(), "defined here.",
+          "Which would clobber the one in your current scope"));
+      err->AppendSubErr(Err(existing_template->function(), "defined here.",
+          "Executing " + desc_string + " should not conflict with anything "
+          "in the current\nscope."));
+      return false;
+    }
+    dest->templates_.insert(*i);
+  }
+
+  return true;
+}
+
+Scope* Scope::MakeTargetDefaults(const std::string& target_type) {
+  if (GetTargetDefaults(target_type))
+    return NULL;
+
+  Scope** dest = &target_defaults_[target_type];
+  if (*dest) {
+    NOTREACHED();  // Already set.
+    return *dest;
+  }
+  *dest = new Scope(settings_);
+  return *dest;
+}
+
+const Scope* Scope::GetTargetDefaults(const std::string& target_type) const {
+  NamedScopeMap::const_iterator found = target_defaults_.find(target_type);
+  if (found != target_defaults_.end())
+    return found->second;
+  if (containing())
+    return containing()->GetTargetDefaults(target_type);
+  return NULL;
+}
+
+const PatternList* Scope::GetSourcesAssignmentFilter() const {
+  if (sources_assignment_filter_)
+    return sources_assignment_filter_.get();
+  if (containing())
+    return containing()->GetSourcesAssignmentFilter();
+  return NULL;
+}
+
+void Scope::SetProcessingBuildConfig() {
+  DCHECK((mode_flags_ & kProcessingBuildConfigFlag) == 0);
+  mode_flags_ |= kProcessingBuildConfigFlag;
+}
+
+void Scope::ClearProcessingBuildConfig() {
+  DCHECK(mode_flags_ & kProcessingBuildConfigFlag);
+  mode_flags_ &= ~(kProcessingBuildConfigFlag);
+}
+
+bool Scope::IsProcessingBuildConfig() const {
+  if (mode_flags_ & kProcessingBuildConfigFlag)
+    return true;
+  if (containing())
+    return containing()->IsProcessingBuildConfig();
+  return false;
+}
+
+void Scope::SetProcessingDefaultBuildConfig() {
+  DCHECK((mode_flags_ & kProcessingDefaultBuildConfigFlag) == 0);
+  mode_flags_ |= kProcessingDefaultBuildConfigFlag;
+}
+
+void Scope::ClearProcessingDefaultBuildConfig() {
+  DCHECK(mode_flags_ & kProcessingDefaultBuildConfigFlag);
+  mode_flags_ &= ~(kProcessingDefaultBuildConfigFlag);
+}
+
+bool Scope::IsProcessingDefaultBuildConfig() const {
+  if (mode_flags_ & kProcessingDefaultBuildConfigFlag)
+    return true;
+  if (containing())
+    return containing()->IsProcessingDefaultBuildConfig();
+  return false;
+}
+
+void Scope::SetProcessingImport() {
+  DCHECK((mode_flags_ & kProcessingImportFlag) == 0);
+  mode_flags_ |= kProcessingImportFlag;
+}
+
+void Scope::ClearProcessingImport() {
+  DCHECK(mode_flags_ & kProcessingImportFlag);
+  mode_flags_ &= ~(kProcessingImportFlag);
+}
+
+bool Scope::IsProcessingImport() const {
+  if (mode_flags_ & kProcessingImportFlag)
+    return true;
+  if (containing())
+    return containing()->IsProcessingImport();
+  return false;
+}
+
+void Scope::SetProperty(const void* key, void* value) {
+  if (!value) {
+    DCHECK(properties_.find(key) != properties_.end());
+    properties_.erase(key);
+  } else {
+    properties_[key] = value;
+  }
+}
+
+void* Scope::GetProperty(const void* key, const Scope** found_on_scope) const {
+  PropertyMap::const_iterator found = properties_.find(key);
+  if (found != properties_.end()) {
+    if (found_on_scope)
+      *found_on_scope = this;
+    return found->second;
+  }
+  if (containing())
+    return containing()->GetProperty(key, found_on_scope);
+  return NULL;
+}
+
+void Scope::AddProvider(ProgrammaticProvider* p) {
+  programmatic_providers_.insert(p);
+}
+
+void Scope::RemoveProvider(ProgrammaticProvider* p) {
+  DCHECK(programmatic_providers_.find(p) != programmatic_providers_.end());
+  programmatic_providers_.erase(p);
+}