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#include "parser.h"
#include "lexer.h"
#include "number.h"
#include <bu/sio.h>
Parser::Parser( Lexer &lex, Bu::Stream &rOut ) :
lex( lex ),
rOut( rOut )
{
}
Parser::~Parser()
{
}
void Parser::parse()
{
for(;;)
{
Token t = lex.nextToken();
switch( t.eType )
{
case Token::tEndOfInput:
return;
case Token::tEndOfLine:
unwind();
if( !tsTerminal.isEmpty() )
{
Bu::println( rOut, "%1").arg( *tsTerminal.peek().nVal );
}
tsTerminal.clear();
break;
case Token::tCommand:
if( *t.sVal == "exit" || *t.sVal == "quit" )
return;
else if( *t.sVal == "scale" )
{
Token t2 = lex.nextToken();
if( t2.eType == Token::tEndOfLine )
{
Bu::println( rOut, "Current scale: %1").
arg( lex.getScale() );
}
else if( t2.eType == Token::tNumber )
{
int32_t i = t2.nVal->toInt32();
lex.setScale( i );
if( i < 0 )
{
Bu::println( rOut, "ERROR: You must provide a "
"positive integer or zero as the parameter "
"to scale.");
}
else
{
Bu::println( rOut, "Scale changed to: %1").
arg( lex.getScale() );
}
}
else
{
Bu::println( rOut, "ERROR: You must provide a number "
"as the parameter to scale.");
}
}
else if( *t.sVal == "radix" )
{
Token t2 = lex.nextToken();
if( t2.eType == Token::tEndOfLine )
{
Bu::println( rOut, "Current radix: %1").
arg( lex.getRadix() );
}
else if( t2.eType == Token::tNumber )
{
int32_t i = t2.nVal->toInt32();
if( i < 2 || i > 36 )
Bu::println( rOut, "ERROR: Radix must be between "
"2 and 36 inclusive");
else
{
lex.setRadix( i );
Bu::println( rOut, "Radix changed to: %1").
arg( lex.getRadix() );
}
}
else
{
Bu::println( rOut, "You must provide a number as "
"the parameter to radix.");
}
}
else
{
Bu::println( rOut, "ERROR: Unknown command '%1'").
arg( *t.sVal );
}
break;
case Token::tNumber:
tsTerminal.push( t );
break;
default:
if( tsNonTerminal.getSize() == 0 ||
getPriority( tsNonTerminal.peek().eType ) <=
getPriority( t.eType ) )
{
// Bu::println("Pushing non-terminal: %1").arg( t.eType );
tsNonTerminal.push( t );
// for( TokenStack::iterator i = tsTerminal.begin(); i; i++ ) Bu::print(" [%1]").arg( *(*i).nVal ); Bu::println("");
// for( TokenStack::iterator i = tsNonTerminal.begin(); i; i++ ) Bu::print(" <%1>").arg( (*i).eType ); Bu::println("");
}
else
{
// Bu::println("Unwinding stack before pushing: %1").arg( t.eType );
unwind();
tsNonTerminal.push( t );
// for( TokenStack::iterator i = tsTerminal.begin(); i; i++ ) Bu::print(" [%1]").arg( *(*i).nVal ); Bu::println("");
// for( TokenStack::iterator i = tsNonTerminal.begin(); i; i++ ) Bu::print(" <%1>").arg( (*i).eType ); Bu::println("");
}
break;
}
}
}
void Parser::unwind()
{
for(;;)
{
// for( TokenStack::iterator i = tsTerminal.begin(); i; i++ ) Bu::print(" [%1]").arg( *(*i).nVal ); Bu::println("");
// for( TokenStack::iterator i = tsNonTerminal.begin(); i; i++ ) Bu::print(" <%1>").arg( (*i).eType ); Bu::println("");
if( tsNonTerminal.isEmpty() )
return;
if( tsTerminal.getSize() < reqTokens( tsNonTerminal.peek().eType ) )
{
return;
}
Token t = tsNonTerminal.peekPop();
switch( t.eType )
{
case Token::tPlus:
{
Token b = tsTerminal.peekPop();
Token a = tsTerminal.peekPop();
tsTerminal.push(
Token( Token::tNumber, new Number( *a.nVal + *b.nVal ) )
);
}
break;
case Token::tMinus:
{
Token b = tsTerminal.peekPop();
Token a = tsTerminal.peekPop();
tsTerminal.push(
Token( Token::tNumber, new Number( *a.nVal - *b.nVal ) )
);
}
break;
case Token::tMultiply:
{
Token b = tsTerminal.peekPop();
Token a = tsTerminal.peekPop();
tsTerminal.push(
Token( Token::tNumber, new Number( *a.nVal * *b.nVal ) )
);
}
break;
case Token::tDivide:
{
Token b = tsTerminal.peekPop();
Token a = tsTerminal.peekPop();
tsTerminal.push(
Token( Token::tNumber, new Number( *a.nVal / *b.nVal ) )
);
}
break;
case Token::tOpenParen:
tsNonTerminal.push( t );
return;
case Token::tCloseParen:
unwind();
if( tsNonTerminal.peek().eType == Token::tOpenParen )
{
tsNonTerminal.pop();
}
else
{
throw Bu::ExceptionBase("Close paren found without open paren.");
}
break;
case Token::tNumber:
case Token::tString:
case Token::tCommand:
case Token::tEndOfLine:
case Token::tEndOfInput:
// These should never show up at all
break;
}
}
}
int Parser::reqTokens( Token::Type eType )
{
switch( eType )
{
case Token::tPlus:
case Token::tMinus:
case Token::tDivide:
case Token::tMultiply:
return 2;
case Token::tOpenParen:
return 0;
case Token::tCloseParen:
return 1;
default:
return 0;
}
}
int Parser::getPriority( Token::Type eType )
{
switch( eType )
{
case Token::tNumber:
case Token::tString:
case Token::tCommand:
return 0;
case Token::tPlus:
case Token::tMinus:
return 1;
case Token::tDivide:
case Token::tMultiply:
return 2;
case Token::tOpenParen:
case Token::tCloseParen:
return 3;
case Token::tEndOfLine:
case Token::tEndOfInput:
return -1;
default:
throw Bu::ExceptionBase("Invalid type in getPriority");
}
}
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