- scanner returns now triple (tok, tok_pos, tok_val)

- initial try-out of AST data structures
- removed test_parser (not working anymore - parser needs more infrastructure)

SVN=128089

usr/gri/gosrc/ast.go

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package AST
+
+import Globals "globals"
+import Universe "universe"
+
+
+export Expr
+type Expr struct {
+	typ *Globals.Type;
+	op int;
+	x, y *Expr;
+}
+
+
+export Stat
+type Stat struct {
+	// To be completed
+}

usr/gri/gosrc/compilation.go

@@ -9,6 +9,7 @@ import Object "object"
 import Type "type"
 import Universe "universe"
 import Scanner "scanner"
+import AST "ast"
 import Parser "parser"
 import Export "export"
 

usr/gri/gosrc/parser.go

@@ -9,6 +9,7 @@ import Globals "globals"
 import Object "object"
 import Type "type"
 import Universe "universe"
+import AST "ast"
 
 
 // So I can submit and have a running parser for now...
@@ -20,9 +21,13 @@ type Parser struct {
 	comp *Globals.Compilation;
 	verbose, indent int;
 	S *Scanner.Scanner;
+	
+	// Token
 	tok int;  // one token look-ahead
-	beg, end int;  // token position
-	ident string;  // last ident seen
+	pos int;  // token source position
+	val string;  // token value (for IDENT, NUMBER, STRING only)
+
+	// Semantic analysis
 	top_scope *Globals.Scope;
 	exports *Globals.List;
 }
@@ -57,13 +62,10 @@ func (P *Parser) Ecart() {
 
 
 func (P *Parser) Next() {
-	P.tok, P.beg, P.end = P.S.Scan();
-	if P.tok == Scanner.IDENT {
-		P.ident = P.S.src[P.beg : P.end];
-	}
+	P.tok, P.pos, P.val = P.S.Scan();
 	if P.verbose > 1 {
 		P.PrintIndent();
-		print "[", P.beg, "] ", Scanner.TokenName(P.tok), "\n";
+		print "[", P.pos, "] ", Scanner.TokenName(P.tok), "\n";
 	}
 }
 
@@ -86,7 +88,7 @@ func (P *Parser) Error(pos int, msg string) {
 
 func (P *Parser) Expect(tok int) {
 	if P.tok != tok {
-		P.Error(P.beg, "expected '" + Scanner.TokenName(tok) + "', found '" + Scanner.TokenName(P.tok) + "'");
+		P.Error(P.pos, "expected '" + Scanner.TokenName(tok) + "', found '" + Scanner.TokenName(P.tok) + "'");
 	}
 	P.Next();  // make progress in any case
 }
@@ -157,7 +159,7 @@ func (P *Parser) ParseIdent() string {
 
 	ident := "";
 	if P.tok == Scanner.IDENT {
-		ident = P.ident;
+		ident = P.val;
 		if P.verbose > 0 {
 			P.PrintIndent();
 			print "Ident = \"", ident, "\"\n";
@@ -175,7 +177,7 @@ func (P *Parser) ParseIdent() string {
 func (P *Parser) ParseIdentDecl(kind int) *Globals.Object {
 	P.Trace("IdentDecl");
 	
-	pos := P.beg;
+	pos := P.pos;
 	obj := Globals.NewObject(pos, kind, P.ParseIdent());
 	P.Declare(obj);
 	
@@ -214,7 +216,7 @@ func (P *Parser) ParseQualifiedIdent() *Globals.Object {
 	P.Trace("QualifiedIdent");
 
 	if EnableSemanticTests {
-		pos := P.beg;
+		pos := P.pos;
 		ident := P.ParseIdent();
 		obj := P.Lookup(ident);
 		if obj == nil {
@@ -250,7 +252,7 @@ func (P *Parser) ParseType() *Globals.Type{
 	
 	typ := P.TryType();
 	if typ == nil {
-		P.Error(P.beg, "type expected");
+		P.Error(P.pos, "type expected");
 		typ = Universe.bad_t;
 	}
 	
@@ -515,7 +517,7 @@ func (P *Parser) TryType() *Globals.Type {
 func (P *Parser) ParseStatement() {
 	P.Trace("Statement");
 	if !P.TryStatement() {
-		P.Error(P.beg, "statement expected");
+		P.Error(P.pos, "statement expected");
 		P.Next();  // make progress
 	}
 	P.Ecart();
@@ -602,7 +604,7 @@ func (P *Parser) ParseOperand() {
 	case Scanner.NEW:
 		P.ParseNew();
 	default:
-		P.Error(P.beg, "operand expected");
+		P.Error(P.pos, "operand expected");
 		P.Next();  // make progress
 	}
 	P.Ecart();
@@ -678,7 +680,7 @@ func (P *Parser) ParsePrimaryExprList() {
 }
 
 
-func (P *Parser) ParseUnaryExpr() {
+func (P *Parser) ParseUnaryExpr() *AST.Expr {
 	P.Trace("UnaryExpr");
 	switch P.tok {
 	case Scanner.ADD: fallthrough;
@@ -691,10 +693,11 @@ func (P *Parser) ParseUnaryExpr() {
 		P.Next();
 		P.ParseUnaryExpr();
 		P.Ecart();
-		return;
+		return nil;  // TODO fix this
 	}
 	P.ParsePrimaryExpr();
 	P.Ecart();
+	return nil;  // TODO fix this
 }
 
 
@@ -718,15 +721,22 @@ func Precedence(tok int) int {
 }
 
 
-func (P *Parser) ParseBinaryExpr(prec1 int) {
+func (P *Parser) ParseBinaryExpr(prec1 int) *AST.Expr {
 	P.Trace("BinaryExpr");
-	P.ParseUnaryExpr();
+	
+	x := P.ParseUnaryExpr();
 	for prec := Precedence(P.tok); prec >= prec1; prec-- {
 		for Precedence(P.tok) == prec {
+			e := new(AST.Expr);
+			e.typ = Universe.undef_t;  // TODO fix this
+			e.op = P.tok;  // TODO should we use tokens or separate operator constants?
+			e.x = x;
 			P.Next();
-			P.ParseBinaryExpr(prec + 1);
+			e.y = P.ParseBinaryExpr(prec + 1);
+			x = e;
 		}
 	}
+	
 	P.Ecart();
 }
 
@@ -1012,7 +1022,7 @@ func (P *Parser) TryStatement() bool {
 	case Scanner.RECV:
 		P.ParseSimpleStat();  // send or receive
 	case Scanner.IDENT:
-		switch P.ident {
+		switch P.val {
 		case "print", "panic":
 			P.ParseBuiltinStat();
 		default:
@@ -1127,7 +1137,7 @@ func (P *Parser) ParseConstDecl() {
 func (P *Parser) ParseTypeSpec() {
 	P.Trace("TypeSpec");
 	
-	pos := P.beg;
+	pos := P.pos;
 	ident := P.ParseIdent();
 	obj := P.top_scope.Lookup(ident);  // only lookup in top scope!
 	if obj != nil {
@@ -1274,7 +1284,7 @@ func (P *Parser) ParseDeclaration() {
 	case Scanner.EXPORT:
 		P.ParseExportDecl();
 	default:
-		P.Error(P.beg, "declaration expected");
+		P.Error(P.pos, "declaration expected");
 		P.Next();  // make progress
 	}
 	if indent != P.indent {

usr/gri/gosrc/scanner.go

@@ -231,17 +231,17 @@ func TokenName(tok int) string {
 }
 
 
-func is_whitespace (ch int) bool {
+func is_whitespace(ch int) bool {
 	return ch == ' ' || ch == '\r' || ch == '\n' || ch == '\t';
 }
 
 
-func is_letter (ch int) bool {
+func is_letter(ch int) bool {
 	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 128 ;
 }
 
 
-func digit_val (ch int) int {
+func digit_val(ch int) int {
 	if '0' <= ch && ch <= '9' {
 		return ch - '0';
 	}
@@ -261,7 +261,7 @@ type Scanner struct {
 	nerrors int;  // number of errors
 	errpos int;  // last error position
 	
-	src string;
+	src string;  // scanned source
 	pos int;  // current reading position
 	ch int;  // one char look-ahead
 	chpos int;  // position of ch
@@ -271,7 +271,7 @@ type Scanner struct {
 // Read the next Unicode char into S.ch.
 // S.ch < 0 means end-of-file.
 //
-func (S *Scanner) Next () {
+func (S *Scanner) Next() {
 	const (
 		Bit1 = 7;
 		Bitx = 6;
@@ -380,7 +380,7 @@ func IsUser(username string) bool {
 }
 
 
-func Init () {
+func Init() {
 	Keywords = new(map [string] int);
 	
 	for i := KEYWORDS_BEG; i <= KEYWORDS_END; i++ {
@@ -433,7 +433,7 @@ func (S *Scanner) Error(pos int, msg string) {
 }
 
 
-func (S *Scanner) Open (filename, src string) {
+func (S *Scanner) Open(filename, src string) {
 	if Keywords == nil {
 		Init();
 	}
@@ -497,7 +497,7 @@ func CharString(ch int) string {
 }
 
 
-func (S *Scanner) Expect (ch int) {
+func (S *Scanner) Expect(ch int) {
 	if S.ch != ch {
 		S.Error(S.chpos, "expected " + CharString(ch) + ", found " + CharString(S.ch));
 	}
@@ -505,14 +505,14 @@ func (S *Scanner) Expect (ch int) {
 }
 
 
-func (S *Scanner) SkipWhitespace () {
+func (S *Scanner) SkipWhitespace() {
 	for is_whitespace(S.ch) {
 		S.Next();
 	}
 }
 
 
-func (S *Scanner) SkipComment () {
+func (S *Scanner) SkipComment() {
 	// '/' already consumed
 	if S.ch == '/' {
 		// comment
@@ -538,33 +538,35 @@ func (S *Scanner) SkipComment () {
 }
 
 
-func (S *Scanner) ScanIdentifier () int {
-	beg := S.pos - 1;
+func (S *Scanner) ScanIdentifier() (tok int, val string) {
+	pos := S.chpos;
 	for is_letter(S.ch) || digit_val(S.ch) < 10 {
 		S.Next();
 	}
-	end := S.pos - 1;
+	val = S.src[pos : S.chpos];
 	
-	var tok int;
 	var present bool;
-	tok, present = Keywords[S.src[beg : end]];
+	tok, present = Keywords[val];
 	if !present {
 		tok = IDENT;
 	}
 	
-	return tok;
+	return tok, val;
 }
 
 
-func (S *Scanner) ScanMantissa (base int) {
+func (S *Scanner) ScanMantissa(base int) {
 	for digit_val(S.ch) < base {
 		S.Next();
 	}
 }
 
 
-func (S *Scanner) ScanNumber (seen_decimal_point bool) int {
+func (S *Scanner) ScanNumber(seen_decimal_point bool) string {
+	pos := S.chpos;
+	
 	if seen_decimal_point {
+		pos--;  // '.' is one byte
 		S.ScanMantissa(10);
 		goto exponent;
 	}
@@ -585,7 +587,7 @@ func (S *Scanner) ScanNumber (seen_decimal_point bool) int {
 			}
 			// octal int
 		}
-		return NUMBER;
+		goto exit;
 	}
 	
 mantissa:
@@ -607,7 +609,9 @@ exponent:
 		}
 		S.ScanMantissa(10);
 	}
-	return NUMBER;
+	
+exit:
+	return S.src[pos : S.chpos];
 }
 
 
@@ -622,7 +626,7 @@ func (S *Scanner) ScanDigits(n int, base int) {
 }
 
 
-func (S *Scanner) ScanEscape () string {
+func (S *Scanner) ScanEscape() string {
 	// TODO: fix this routine
 	
 	ch := S.ch;
@@ -654,9 +658,10 @@ func (S *Scanner) ScanEscape () string {
 }
 
 
-func (S *Scanner) ScanChar () int {
+func (S *Scanner) ScanChar() string {
 	// '\'' already consumed
 
+	pos := S.chpos - 1;
 	ch := S.ch;
 	S.Next();
 	if ch == '\\' {
@@ -664,11 +669,11 @@ func (S *Scanner) ScanChar () int {
 	}
 
 	S.Expect('\'');
-	return NUMBER;
+	return S.src[pos : S.chpos];
 }
 
 
-func (S *Scanner) ScanString () int {
+func (S *Scanner) ScanString() string {
 	// '"' already consumed
 
 	pos := S.chpos - 1;
@@ -683,13 +688,13 @@ func (S *Scanner) ScanString () int {
 			S.ScanEscape();
 		}
 	}
-
+	
 	S.Next();
-	return STRING;
+	return S.src[pos : S.chpos];
 }
 
 
-func (S *Scanner) ScanRawString () int {
+func (S *Scanner) ScanRawString() string {
 	// '`' already consumed
 
 	pos := S.chpos - 1;
@@ -703,11 +708,11 @@ func (S *Scanner) ScanRawString () int {
 	}
 
 	S.Next();
-	return STRING;
+	return S.src[pos : S.chpos];
 }
 
 
-func (S *Scanner) Select2 (tok0, tok1 int) int {
+func (S *Scanner) Select2(tok0, tok1 int) int {
 	if S.ch == '=' {
 		S.Next();
 		return tok1;
@@ -716,7 +721,7 @@ func (S *Scanner) Select2 (tok0, tok1 int) int {
 }
 
 
-func (S *Scanner) Select3 (tok0, tok1, ch2, tok2 int) int {
+func (S *Scanner) Select3(tok0, tok1, ch2, tok2 int) int {
 	if S.ch == '=' {
 		S.Next();
 		return tok1;
@@ -729,7 +734,7 @@ func (S *Scanner) Select3 (tok0, tok1, ch2, tok2 int) int {
 }
 
 
-func (S *Scanner) Select4 (tok0, tok1, ch2, tok2, tok3 int) int {
+func (S *Scanner) Select4(tok0, tok1, ch2, tok2, tok3 int) int {
 	if S.ch == '=' {
 		S.Next();
 		return tok1;
@@ -746,27 +751,27 @@ func (S *Scanner) Select4 (tok0, tok1, ch2, tok2, tok3 int) int {
 }
 
 
-func (S *Scanner) Scan () (tok, beg, end int) {
+func (S *Scanner) Scan() (tok, pos int, val string) {
 	S.SkipWhitespace();
 	
 	ch := S.ch;
 	tok = ILLEGAL;
-	beg = S.chpos;
-
+	pos = S.chpos;
+	
 	switch {
-	case is_letter(ch): tok = S.ScanIdentifier();
-	case digit_val(ch) < 10: tok = S.ScanNumber(false);
+	case is_letter(ch): tok, val = S.ScanIdentifier();
+	case digit_val(ch) < 10: tok, val = NUMBER, S.ScanNumber(false);
 	default:
 		S.Next();  // always make progress
 		switch ch {
 		case -1: tok = EOF;
-		case '"': tok = S.ScanString();
-		case '\'': tok = S.ScanChar();
-		case '`': tok = S.ScanRawString();
+		case '"': tok, val = STRING, S.ScanString();
+		case '\'': tok, val = NUMBER, S.ScanChar();
+		case '`': tok, val = STRING, S.ScanRawString();
 		case ':': tok = S.Select2(COLON, DEFINE);
 		case '.':
 			if digit_val(S.ch) < 10 {
-				tok = S.ScanNumber(true);
+				tok, val = NUMBER, S.ScanNumber(true);
 			} else {
 				tok = PERIOD;
 			}
@@ -791,8 +796,8 @@ func (S *Scanner) Scan () (tok, beg, end int) {
 			if S.ch == '/' || S.ch == '*' {
 				S.SkipComment();
 				// cannot simply return because of 6g bug
-				tok, beg, end = S.Scan();
-				return tok, beg, end;
+				tok, pos, val = S.Scan();
+				return tok, pos, val;
 			}
 			tok = S.Select2(QUO, QUO_ASSIGN);
 		case '%': tok = S.Select2(REM, REM_ASSIGN);
@@ -810,10 +815,10 @@ func (S *Scanner) Scan () (tok, beg, end int) {
 		case '&': tok = S.Select3(AND, AND_ASSIGN, '&', LAND);
 		case '|': tok = S.Select3(OR, OR_ASSIGN, '|', LOR);
 		default:
-			S.Error(beg, "illegal character " + CharString(ch));
+			S.Error(pos, "illegal character " + CharString(ch));
 			tok = ILLEGAL;
 		}
 	}
 	
-	return tok, beg, S.chpos;
+	return tok, pos, val;
 }

usr/gri/gosrc/test_parser.go

-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package main
-
-import Globals "globals"  // to get rid od 6g warning only
-import Scanner "scanner"
-import Parser "parser"
-
-
-func Parse(filename, src string, verbose int) {
-	S := new(Scanner.Scanner);
-	S.Open(filename, src);
-	
-	P := new(Parser.Parser);
-	P.Open(nil, S, verbose);
-	
-	P.ParseProgram();
-}
-
-
-func main() {
-	verbose := 0;
-	for i := 1; i < sys.argc(); i++ {
-		switch sys.argv(i) {
-		case "-v":
-			verbose = 1;
-			continue;
-		case "-vv":
-			verbose = 2;
-			continue;
-		}
-		
-		src, ok := sys.readfile(sys.argv(i));
-		if ok {
-			print "parsing " + sys.argv(i) + "\n";
-			Parse(sys.argv(i), src, verbose);
-		} else {
-			print "error: cannot read " + sys.argv(i) + "\n";
-		}
-	}
-}

usr/gri/gosrc/test_scanner.go

@@ -11,8 +11,12 @@ func Scan(filename, src string) {
 	S := new(Scanner.Scanner);
 	S.Open(filename, src);
 	for {
-		tok, beg, end := S.Scan();
-		print Scanner.TokenName(tok), "\t ", src[beg : end], "\n";
+		tok, pos, val := S.Scan();
+		print pos, ": ", Scanner.TokenName(tok);
+		if tok == Scanner.IDENT || tok == Scanner.NUMBER || tok == Scanner.STRING {
+			print " ", val;
+		}
+		print "\n";
 		if tok == Scanner.EOF {
 			return;
 		}