simpliest c++ example

README.md

@@ -1,30 +0,0 @@
-# Parser
-## Explanation of options:
-```cpp
-// Bison version
-%require "3.0.4"
-
-// skeleton program to be used as parser
-%skeleton "lalr1.cc" 
-
-// tells bison to generate a header file
-%defines 
-
-// where the parser will live (in what namespace)
-%define api.prefix {yy} 
-
-// the name of parser class
-%define api.parser.class {Parser} 
-
-/* it will generate a location class which can be used in your lexer */
-%locations
-
-/* use the constructor for each token, and make_TOKENNAME functions will be generated */
-%define api.token.constructor 
-
-/* use the variant type for $1~$n and $$ those variables */
-%define api.value.type variant
-
-%define parse.trace
-%define parse.error verbose
-```

makefile

@@ -5,29 +5,20 @@ FLEX = flex
 
 TARGET = build/py2rb
 
-$(TARGET): build/lexer.o build/parser.o build/ParserCtx.o  build/main.o build/config.o
+$(TARGET): build/parser.o build/lexer.o build/main.o
 	$(CXX) $^ -o $@
 
-build/lexer.hpp build/lexer.cpp: src/lexer.l build/parser.hpp build
+build/parser.cpp build/parser.hpp: src/parser.y | build
+	$(BISON) -d -o build/parser.cpp src/parser.y
+
+build/lexer.cpp build/lexer.hpp: src/lexer.l build/parser.hpp | build
 	$(FLEX) --header-file=build/lexer.hpp -o build/lexer.cpp src/lexer.l
 
-build/parser.hpp build/parser.cpp: src/parser.y build
-	$(BISON) -d -v -o build/parser.cpp src/parser.y
+build/%.o: build/%.cpp
+	$(CXX) -c $(ARGS) $< -o $@
 
-build/lexer.o: build/lexer.cpp build
-	$(CXX) -c $(ARGS)  $< -o $@
-
-build/parser.o: build/parser.cpp build
-	$(CXX) -c $(ARGS)  $< -o $@
-
-build/ParserCtx.o: src/ParserCtx.cpp build
-	$(CXX) -c $(ARGS)  $< -o $@
-
-build/main.o: src/main.cpp build
-	$(CXX) -c $(ARGS)  $< -o $@
-
-build/config.o: src/config.cpp build
-	$(CXX) -c $(ARGS)  $< -o $@
+build/main.o: src/main.cpp | build
+	$(CXX) -c $(ARGS) $< -o $@
 
 build:
 	mkdir -p build
@@ -38,7 +29,4 @@ clean:
 run: $(TARGET)
 	$(TARGET)
 
-run_lexer: $(TARGET)
-	$(TARGET) -l
-
 .PHONY: clean run

src/ParserCtx.cpp

@@ -1,18 +0,0 @@
-#include "ParserCtx.hpp"
-#include "../build/lexer.hpp"
-#include "../build/parser.hpp"
-
-ParserCtx::ParserCtx()
-{
-    yylex_init(&lexer);
-    // yyset_in()
-    loc = new yy::location();
-    parser = new yy::Parser(lexer, *loc, *this);
-}
-
-ParserCtx::~ParserCtx()
-{
-    yylex_destroy(lexer);
-    delete loc;
-    delete parser;
-}

src/ParserCtx.hpp

@@ -1,18 +0,0 @@
-#pragma once
-
-namespace yy
-{
-    class Parser;
-    class location;
-}
-
-class ParserCtx
-{
-public:
-    ParserCtx();
-    ~ParserCtx();
-
-    void *lexer;
-    yy::location *loc;
-    yy::Parser *parser;
-};

src/config.cpp

@@ -1,25 +0,0 @@
-#include "config.hpp"
-#include <unistd.h>
-#include <stdexcept>
-
-Configuration::Configuration(int argc, char **argv)
-{
-    int opt;
-    while ((opt = getopt(argc, argv, "i:o:l")) != -1)
-    {
-        switch (opt)
-        {
-        case 'i':
-            input_file = optarg;
-            break;
-        case 'o':
-            output_file = optarg;
-            break;
-        case 'l':
-            debug_lexer = true;
-            break;
-        default:
-            throw std::runtime_error("Invalid arguments");
-        }
-    }
-}

src/config.hpp

@@ -1,12 +0,0 @@
-#pragma once
-#include <string>
-
-class Configuration
-{
-public:
-    std::string input_file;
-    std::string output_file;
-    bool debug_lexer = false;
-
-    Configuration(int argc, char **argv);
-};

src/lexer.l

@@ -1,28 +1,35 @@
-%option reentrant noyywrap nounput
+%option c++
+%option noyywrap
+%option yyclass="Scanner"
 
 %{
-#include <iostream>
 #include "../build/parser.hpp"
+#include <string>
 
-#define YY_DECL yy::Parser::symbol_type yylex(yyscan_t yyscanner, yy::location& loc)
+class Scanner : public yyFlexLexer {
+public:
+    Scanner(std::istream* in) : yyFlexLexer(in) {}
     
-#define YY_USER_ACTION loc.columns(yyleng);
-#define yyterminate() return yy::Parser::make_END(loc)
+    int yylex(); 
 
+    int lex(yy::parser::semantic_type* yylval) {
+        this->yylval = yylval;
+        return yylex();
+    }
     
+private:
+    yy::parser::semantic_type* yylval;
+};
+
+int scanner_lex(yy::parser::semantic_type* yylval) {
+    static Scanner scanner(&std::cin);
+    return scanner.lex(yylval);
+}
 %}
 
 %%
-
-%{
-	loc.step();
-%}
-
-
-function       	{return yy::Parser::make_FUNCTION(loc);}
-
-[ \n\r\t\v]		{}
-
-.				{std::cerr << loc << ": " << "token error" << std::endl; exit(1);}
-
+[0-9]+          { return yy::parser::token::TOK_NUMBER; }
+[a-zA-Z]+       { yylval->as<std::string>() = yytext; return yy::parser::token::TOK_WORD; }
+[ \t\r\n]+      { /* skip */ }
+.               { return yy::parser::token::TOK_CHAR; }
 %%

src/main.cpp

@@ -1,41 +1,7 @@
 #include "../build/parser.hpp"
-#include "../build/lexer.hpp"
-#include "../src/config.hpp"
-#include "../src/ParserCtx.hpp"
-#include <iostream>
-#include <fstream>
 
-yy::Parser::symbol_type yylex(yyscan_t yyscanner, yy::location &loc);
-
-void dump_tokens(ParserCtx &ctx)
+int main()
 {
-    while (true)
-    {
-        auto tok = yylex(ctx.lexer, *ctx.loc);
-
-        std::cout
-            << "Token: "
-            << yy::Parser::symbol_name(tok.kind())
-            << ", Location: " << tok.location
-            << '\n';
-
-        if (tok.kind() == yy::Parser::symbol_kind::S_YYEOF)
-        {
-            break;
-        }
-    }
-}
-
-int main(int argc, char *argv[])
-{
-    ParserCtx ctx;
-    Configuration config(argc, argv);
-
-    if (config.debug_lexer)
-    {
-        dump_tokens(ctx);
-        return 0;
-    }
-
-    return ctx.parser->parse();
+    yy::parser p;
+    return p.parse();
 }

src/parser.y

@@ -1,51 +1,45 @@
-%require "3.0.4"
 %skeleton "lalr1.cc"
+%require "3.0"
 %defines
-%define api.prefix {yy} 
-%define api.parser.class {Parser} 
-%locations
-%define api.token.constructor 
 %define api.value.type variant
-%define parse.trace
-%define parse.error verbose
+%define api.parser.class { parser }
+%define api.namespace { yy }
+%define api.token.prefix {TOK_}
 
-
-%code requires
-{
-#include <list>
-#include <string>
-#include <functional>
-#include "../src/ParserCtx.hpp"
+%code requires {
+    #include <string>
 }
 
-%code
-{
-yy::Parser::symbol_type yylex(void* yyscanner, yy::location& loc);
+%code {
+    #include <iostream>
+    
+    int scanner_lex(yy::parser::semantic_type* yylval);
+    
+    #undef yylex
+    #define yylex scanner_lex
 }
 
+%token <std::string> WORD
+%token NUMBER
+%token CHAR
 
-%token END 0;
-%token FUNCTION
-
-
-/* The driver is passed by reference to the parser and to the scanner. This
- * provides a simple but effective pure interface, not relying on global
- * variables. */
-%lex-param {void *scanner} {yy::location& loc}
-%parse-param {void *scanner} {yy::location& loc} { class ParserCtx& ctx }
-
+%%
+input:
+      /* empty */
+    | input element
+    ;
 
+element:
+      WORD   { std::cout << "WORD: " << $1 << "\n"; }
+    | NUMBER { std::cout << "NUMBER\n"; }
+    | CHAR   { std::cout << "CHAR\n"; }
+    ;
 
 %%
 
-%start program;
-
-program: FUNCTION;
-
-
-%%
-
-void yy::Parser::error(const yy::location& l, const std::string& m)
-{
-	std::cerr << l << ": " << m << std::endl;
+namespace yy {
+    void parser::error(const std::string& msg)
+    {
+        std::cerr << "Error: " << msg << "\n";
+    }
 }