From a4635fb95235ba4bf077bd59957da0626fc5ba72 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbarenblat@gmail.com>
Date: Tue, 14 Dec 2021 12:34:06 -0500
Subject: EC, a terminal-based RPN calculator

---
 src/parser_driver.cc | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 src/parser_driver.cc

(limited to 'src/parser_driver.cc')

diff --git a/src/parser_driver.cc b/src/parser_driver.cc
new file mode 100644
index 0000000..60e59ab
--- /dev/null
+++ b/src/parser_driver.cc
@@ -0,0 +1,71 @@
+// Copyright 2021 Benjamin Barenblat
+//
+// 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
+//
+//     https://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.
+
+#include "src/parser_driver.h"
+
+#include <antlr4-runtime.h>
+
+#include <memory>
+#include <vector>
+
+#include "src/CalculatorBaseVisitor.h"
+#include "src/CalculatorLexer.h"
+#include "src/CalculatorParser.h"
+#include "src/language.h"
+#include "third_party/abseil/absl/strings/string_view.h"
+
+namespace ec {
+
+namespace {
+
+template <typename T, typename... Args>
+std::shared_ptr<const Term> MakeTerm(Args... args) {
+  return std::static_pointer_cast<const Term>(std::make_shared<T>(args...));
+}
+
+class Visitor : public CalculatorBaseVisitor {
+ public:
+  antlrcpp::Any visitProgram(CalculatorParser::ProgramContext* ctx) override {
+    Program p;
+    for (CalculatorParser::TermContext* term : ctx->term()) {
+      p.push_back(visit(term));
+    }
+    return p;
+  }
+
+  antlrcpp::Any visitNumber(CalculatorParser::NumberContext* ctx) override {
+    return MakeTerm<GroundTerm>(ctx->value);
+  }
+
+  antlrcpp::Any visitIdentifier(
+      CalculatorParser::IdentifierContext* ctx) override {
+    return MakeTerm<SymbolTerm>(ctx->value);
+  }
+
+  antlrcpp::Any visitError(CalculatorParser::ErrorContext*) override {
+    throw ParseError();
+  }
+};
+
+}  // namespace
+
+Program ParseFromString(absl::string_view text) {
+  antlr4::ANTLRInputStream input(text.data(), text.size());
+  CalculatorLexer lexer(&input);
+  antlr4::CommonTokenStream tokens(&lexer);
+  CalculatorParser parser(&tokens);
+  return Visitor().visit(parser.program());
+}
+
+}  // namespace ec
-- 
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