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Update README.md calculator example to match source code

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Charles Baker 2019-04-20 20:15:34 +12:00
parent ae4ed8104c
commit 658bc53969
1 changed files with 32 additions and 38 deletions
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70
README.md
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@ -16,7 +16,6 @@ Modern [LALR(1)](https://en.wikipedia.org/wiki/LALR_parser) parser generator and
## Example
~~~c++
#include <stdio.h>
#include <stdarg.h>
#include <lalr/GrammarCompiler.hpp>
@ -26,36 +25,6 @@ Modern [LALR(1)](https://en.wikipedia.org/wiki/LALR_parser) parser generator and
using namespace std;
using namespace lalr;
static int add( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return start[0].user_data() + start[2].user_data();
}
static int subtract( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return start[0].user_data() - start[2].user_data();
}
static int multiply( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return start[0].user_data() * start[2].user_data();
}
static int divide( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return start[0].user_data() / start[2].user_data();
}
static int compound( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return start[1].user_data();
}
static int integer( const ParserNode<int>* start, const ParserNode<int>* finish )
{
return ::atoi( start[0].lexeme().c_str() );
}
void lalr_calculator_example()
{
const char* calculator_grammar =
@ -80,16 +49,41 @@ void lalr_calculator_example()
compiler.compile( calculator_grammar, calculator_grammar + strlen(calculator_grammar) );
Parser<const char*, int> parser( compiler.parser_state_machine() );
parser.parser_action_handlers()
( "add", &add )
( "subtract", &subtract )
( "multiply", &multiply )
( "divide", &divide )
( "compound", &compound )
( "integer", &integer )
( "add", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return data[0] + data[2];
}
)
( "subtract", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return data[0] - data[2];
}
)
( "multiply", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return data[0] * data[2];
}
)
( "divide", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return data[0] / data[2];
}
)
( "compound", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return data[1];
}
)
( "integer", [] ( const int* data, const ParserNode<>* nodes, size_t length )
{
return ::atoi( nodes[0].lexeme().c_str() );
}
)
;
const char* input = "1 + 2 * (3 + 4) + 5";
parser.parse( input, input + strlen(input) );
printf( "1 + 2 * (3 + 4) + 5 = %d", parser.user_data() );
LALR_ASSERT( parser.accepted() );
LALR_ASSERT( parser.full() );
LALR_ASSERT( parser.user_data() == 20 );