101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
// Copyright 2020 The Tint Authors. //
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef SRC_SCOPE_STACK_H_
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#define SRC_SCOPE_STACK_H_
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#include <string>
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#include <unordered_map>
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#include <vector>
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namespace tint {
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/// Used to store a stack of scope information.
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/// The stack starts with a global scope which can not be popped.
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template <class T>
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class ScopeStack {
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public:
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/// Constructor
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ScopeStack() {
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// Push global bucket
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stack_.push_back({});
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}
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/// Copy Constructor
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ScopeStack(const ScopeStack&) = default;
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~ScopeStack() = default;
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/// Push a new scope on to the stack
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void push_scope() { stack_.push_back({}); }
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/// Pop the scope off the top of the stack
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void pop_scope() {
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if (stack_.size() > 1) {
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stack_.pop_back();
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}
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}
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/// Set a global variable in the stack
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/// @param name the name of the variable
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/// @param val the value
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void set_global(const std::string& name, T val) { stack_[0][name] = val; }
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/// Sets variable into the top most scope of the stack
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/// @param name the name of the variable
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/// @param val the value
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void set(const std::string& name, T val) { stack_.back()[name] = val; }
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/// Checks for the given |name| in the stack
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/// @param name the name to look for
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/// @returns true if the stack contains |name|
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bool has(const std::string& name) const { return get(name, nullptr); }
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/// Retrieves a given name from the stack
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/// @param name the name to look for
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/// @param ret where to place the name
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/// @returns true if the name was successfully found, false otherwise
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bool get(const std::string& name, T* ret) const {
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return get(name, ret, nullptr);
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}
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/// Retrieves a given name from the stack
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/// @param name the name to look for
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/// @param ret where to place the name
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/// @param is_global set true if the name references a global variable
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/// otherwise unchanged
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/// @returns true if the name was successfully found, false otherwise
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bool get(const std::string& name, T* ret, bool* is_global) const {
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for (auto iter = stack_.rbegin(); iter != stack_.rend(); ++iter) {
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auto& map = *iter;
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auto val = map.find(name);
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if (val != map.end()) {
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if (ret) {
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*ret = val->second;
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}
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if (is_global && iter == stack_.rend() - 1) {
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*is_global = true;
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}
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return true;
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}
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}
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return false;
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}
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private:
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std::vector<std::unordered_map<std::string, T>> stack_;
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};
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} // namespace tint
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#endif // SRC_SCOPE_STACK_H_
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