From 3015ea4677201060777435cf76815e898d221f8c Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Thu, 1 Dec 2016 09:31:45 -0700
Subject: The parser works.
There's still more to do, however. It doesn't do math anymore, it produces
a script that can then be executed. Now we have to capture that script and
execute it.
---
src/lexer.cpp | 24 ++-----
src/parser.cpp | 213 +++++++++++++++++++++++++++++++++++++++++++++++----------
src/parser.h | 4 +-
src/token.cpp | 12 ++++
src/token.h | 4 +-
5 files changed, 201 insertions(+), 56 deletions(-)
diff --git a/src/lexer.cpp b/src/lexer.cpp
index 538e088..87d603a 100644
--- a/src/lexer.cpp
+++ b/src/lexer.cpp
@@ -6,7 +6,7 @@
Lexer::Lexer( Bu::Stream &rIn ) :
rIn( rIn ),
- iBufPos( 0 ),
+ iBufPos( -1 ),
iScale( 0 ),
iRadix( 10 ),
numRangeTop('9'),
@@ -55,28 +55,12 @@ void Lexer::fillToken()
default:
throw Bu::ExceptionBase("Invalid mode.");
}
-/*
- Bu::sio << "read["
- << ((iLookAheadUsed+iLookAheadStart)%iLookAheadSize)
- << "]: "
- << aLookAhead[(iLookAheadUsed+iLookAheadStart)%iLookAheadSize].eType;
- if( aLookAhead[(iLookAheadUsed+iLookAheadStart)%iLookAheadSize].eType == Token::tNumber )
- Bu::sio << "("
- << aLookAhead[(iLookAheadUsed+iLookAheadStart)%iLookAheadSize].nVal->toString() << ")";
- Bu::sio << Bu::sio.nl;
-*/
}
Token Lexer::nextTokenNormal()
{
for(;;)
{
- if( iBufPos >= sBuf.getSize() )
- {
- iBufPos = -1;
- return Token( Token::tEndOfLine );
- }
-
if( iBufPos < 0 )
{
if( rIn.isEos() )
@@ -90,8 +74,12 @@ Token Lexer::nextTokenNormal()
}
iBufPos = 0;
}
+ if( iBufPos >= sBuf.getSize() )
+ {
+ iBufPos = -1;
+ return Token( Token::tEndOfLine );
+ }
- //Bu::println("Testing char '%1' at %2").arg( sBuf[iBufPos] ).arg( iBufPos );
switch( sBuf[iBufPos] )
{
case ' ':
diff --git a/src/parser.cpp b/src/parser.cpp
index 510b471..f88ffe7 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -26,49 +26,34 @@ void Parser::parse()
if( lex[0].eType == Token::tEndOfInput )
break;
- expr();
+ exprR();
+ reduce();
- Bu::sio << "Final stack:";
- for( TokenStack::iterator i = tsParse.begin(); i; i++ )
- {
- Bu::sio << " " << (*i).eType;
- if( (*i).eType == Token::tNumber )
- {
- Bu::sio << "(" << (*i).nVal->toString() << ")";
- }
- }
- Bu::sio << Bu::sio.nl;
- Bu::sio << "Script:";
- for( TokenStack::iterator i = tsScript.begin(); i; i++ )
- {
- Bu::sio << " " << (*i).eType;
- if( (*i).eType == Token::tNumber )
- {
- Bu::sio << "(" << (*i).nVal->toString() << ")";
- }
- }
- Bu::sio << Bu::sio.nl;
+ printState("Final");
+
+ tsParse.clear();
+ tsScript.clear();
}
}
+void Parser::exprR()
+{
+ exprP();
+ expr();
+}
+
void Parser::expr()
{
+ Bu::sio << "::expr " << lex[0] << Bu::sio.nl;
if( lex[0].eType == Token::tEndOfInput )
return;
- if( lex[0].eType == Token::tVariable &&
- lex[1].eType == Token::tEquals )
- {
- Token t = lex[0];
- lex.nextToken();
- lex.nextToken();
- expr();
-
- return;
- }
- exprP();
switch( lex[0].eType )
{
+ case Token::tEquals:
+ throw Bu::ExceptionBase("misplaced equals.");
+ break;
+
case Token::tPlus:
case Token::tMinus:
case Token::tMultiply:
@@ -76,30 +61,111 @@ void Parser::expr()
case Token::tModulus:
Token t = lex[0];
lex.nextToken();
- expr();
- shift( t );
+ Bu::sio << "->expr " << t << " " << lex[0] << Bu::sio.nl;
+ if( lex[0].eType == Token::tOpenParen )
+ {
+ exprP();
+ shift( t );
+ reduce();
+ expr();
+ }
+ else
+ {
+ if( lex[0].eType == Token::tNumber ||
+ lex[0].eType == Token::tVariable )
+ {
+ Bu::sio << "->expr " << t <<
+ " " << lex[0] <<
+ " " << lex[1] <<
+ Bu::sio.nl;
+ shift( lex[0] );
+ if( lex[1].eType == Token::tPlus ||
+ lex[1].eType == Token::tMinus ||
+ lex[1].eType == Token::tDivide ||
+ lex[1].eType == Token::tMultiply ||
+ lex[1].eType == Token::tModulus ||
+ lex[1].eType == Token::tEquals )
+ {
+ if( getPriority(lex[1].eType) <=
+ getPriority(t.eType) )
+ {
+ shift( t );
+ reduce();
+ printState("reduce");
+ lex.nextToken();
+ expr();
+ }
+ else
+ {
+ printState("no reduce");
+ lex.nextToken();
+ expr();
+ if( !tsParse.isEmpty() &&
+ tsParse.peek().eType != Token::tComputedValue )
+ {
+ reduce();
+ printState("no reduce reduce");
+ }
+ shift( t );
+ printState("post no reduce");
+ }
+ }
+ else
+ {
+ shift( t );
+ lex.nextToken();
+ printState("no next op");
+ }
+ }
+ else
+ {
+ Bu::println("???");
+ }
+ }
break;
}
}
void Parser::exprP()
{
+ if( lex[0].eType == Token::tVariable &&
+ lex[1].eType == Token::tEquals )
+ {
+ Token t = lex[0];
+ lex.nextToken( 2 );
+ exprR();
+ reduce();
+ printState("pre-equals");
+ shift( t );
+ shift( Token( Token::tEquals ) );
+ printState("post-equals");
+ reduce();
+ printState("post-equals-reduce");
+ return;
+ }
+
switch( lex[0].eType )
{
case Token::tNumber:
case Token::tVariable:
- shift( lex[0] );
+ shift( lex[0] );
lex.nextToken();
break;
case Token::tOpenParen:
+ shift( lex[0] );
lex.nextToken();
- expr();
+ exprR();
if( lex[0].eType != Token::tCloseParen )
{
+ Bu::sio << "::exprP " << lex[0] << Bu::sio.nl;
throw Bu::ExceptionBase("Expected close paren");
}
+ shift( lex[0] );
+ printState("closeParen");
+ reduce();
lex.nextToken();
+ printState("post closeParen");
break;
case Token::tMinus:
@@ -206,6 +272,63 @@ void Parser::shift( const Token &t )
void Parser::reduce()
{
+ if( tsParse.isEmpty() || tsParse.peek().eType == Token::tOpenParen )
+ return;
+ Token tOp = tsParse.peekPop();
+ switch( tOp.eType )
+ {
+ case Token::tNumber:
+ case Token::tVariable:
+ tsScript.append( tOp );
+ tsParse.push( Token( Token::tComputedValue ) );
+ break;
+
+ case Token::tComputedValue:
+ tsParse.push( Token( Token::tComputedValue ) );
+ break;
+
+ case Token::tPlus:
+ case Token::tMinus:
+ case Token::tDivide:
+ case Token::tMultiply:
+ case Token::tModulus:
+ case Token::tEquals:
+ for(int j = 0; j < 2; j++ )
+ {
+ Token t = tsParse.peekPop();
+ if( t.eType == Token::tNumber ||
+ t.eType == Token::tVariable )
+ {
+ tsScript.append( t );
+ }
+ else if( t.eType == Token::tComputedValue )
+ {
+ // Nope, we don't care
+ }
+ }
+ tsScript.append( tOp );
+ shift( Token( Token::tComputedValue ) );
+ break;
+
+ case Token::tCloseParen:
+ if( tsParse.peek().eType != Token::tComputedValue )
+ {
+ printState("paren-innerReduce-pre");
+ reduce();
+ printState("paren-innerReduce-post");
+ }
+ tsParse.pop();
+ if( tsParse.peek().eType == Token::tOpenParen )
+ {
+ tsParse.pop();
+ shift( Token( Token::tComputedValue ) );
+ }
+ else
+ {
+ throw Bu::ExceptionBase("Error?");
+ }
+ break;
+ }
}
int Parser::reqTokens( Token::Type eType )
@@ -263,3 +386,21 @@ int Parser::getPriority( Token::Type eType )
}
}
+void Parser::printState( const Bu::String &sTag )
+{
+ Bu::sio << "----------------" << Bu::sio.nl;
+ Bu::sio << sTag << " stack:";
+ for( TokenStack::iterator i = tsParse.begin(); i; i++ )
+ {
+ Bu::sio << " " << (*i);
+ }
+ Bu::sio << Bu::sio.nl;
+ Bu::sio << sTag << " script:";
+ for( TokenStack::iterator i = tsScript.begin(); i; i++ )
+ {
+ Bu::sio << " " << (*i);
+ }
+ Bu::sio << Bu::sio.nl;
+ Bu::sio << "----------------" << Bu::sio.nl;
+}
+
diff --git a/src/parser.h b/src/parser.h
index 1caa229..b0a1231 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -53,13 +53,15 @@ public:
private:
void expr();
void exprP();
+ void exprR();
private:
void shift( const Token &t );
void reduce();
int reqTokens( Token::Type eType );
int getPriority( Token::Type eType );
- Number &deref( Token &t );
+
+ void printState( const Bu::String &sTag );
private:
Lexer &lex;
diff --git a/src/token.cpp b/src/token.cpp
index 1eaa92a..0c7bda1 100644
--- a/src/token.cpp
+++ b/src/token.cpp
@@ -100,8 +100,20 @@ Bu::Formatter &operator<<( Bu::Formatter &f, Token::Type eType )
case Token::tEndOfLine: return f << "eol";
case Token::tEndOfInput: return f << "eoi";
case Token::tNegate: return f << "neg";
+ case Token::tUninitialized: return f << "<->";
+ case Token::tComputedValue: return f << "cmp";
default: return f << "???";
}
}
+Bu::Formatter &operator<<( Bu::Formatter &f, const Token &t )
+{
+ f << t.eType;
+ if( t.eType == Token::tNumber )
+ f << "(" << (t.nVal?t.nVal->toString():"<null>") << ")";
+ else if( t.eType == Token::tString || t.eType == Token::tVariable )
+ f << "(" << (t.sVal?*(t.sVal):"<null>") << ")";
+ return f;
+}
+
diff --git a/src/token.h b/src/token.h
index 8d7dc20..072a96b 100644
--- a/src/token.h
+++ b/src/token.h
@@ -31,7 +31,8 @@ public:
tEndOfInput,
- tUninitialized
+ tUninitialized,
+ tComputedValue
};
Token();
@@ -52,5 +53,6 @@ public:
};
Bu::Formatter &operator<<( Bu::Formatter &f, Token::Type eType );
+Bu::Formatter &operator<<( Bu::Formatter &f, const Token &t );
#endif
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