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- improved error handling

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SVN=126718
This commit is contained in:
Robert Griesemer 2008-07-10 14:42:33 -07:00
parent 9ec762791e
commit 8be580e20d
4 changed files with 56 additions and 51 deletions
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19
usr/gri/src/parser.go
View File

@ -4,7 +4,6 @@
package Parser
//import . "scanner"
import Scanner "scanner"
@ -63,8 +62,8 @@ func (P *Parser) Open(S *Scanner.Scanner, verbose int) {
}
func (P *Parser) Error(msg string) {
P.S.Error(P.S.pos, msg);
func (P *Parser) Error(pos int, msg string) {
P.S.Error(pos, msg);
P.Next(); // make progress
}
@ -73,7 +72,7 @@ func (P *Parser) Expect(tok int) {
if P.tok == tok {
P.Next()
} else {
P.Error("expected `" + Scanner.TokenName(tok) + "`, found `" + Scanner.TokenName(P.tok) + "`");
P.Error(P.beg, "expected '" + Scanner.TokenName(tok) + "', found '" + Scanner.TokenName(P.tok) + "'");
}
}
@ -130,7 +129,7 @@ func (P *Parser) ParseTypeName() {
func (P *Parser) ParseType() {
P.Trace("Type");
if !P.TryType() {
P.Error("type expected");
P.Error(P.beg, "type expected");
}
P.Ecart();
}
@ -583,7 +582,7 @@ func (P *Parser) ParseControlFlowStat(tok int) {
func (P *Parser) ParseStatement() {
P.Trace("Statement");
if !P.TryStatement() {
P.Error("statement expected");
P.Error(P.beg, "statement expected");
}
P.Ecart();
}
@ -874,7 +873,7 @@ func (P *Parser) ParseDeclaration() {
case Scanner.EXPORT:
P.ParseExportDecl();
default:
P.Error("declaration expected");
P.Error(P.beg, "declaration expected");
}
if indent != P.indent {
panic "imbalanced tracing code"
@ -916,7 +915,7 @@ func (P *Parser) ParseOperand() {
case Scanner.NEW:
P.ParseNew();
default:
P.Error("operand expected");
P.Error(P.beg, "operand expected");
}
P.Ecart();
}
@ -1004,9 +1003,9 @@ func (P *Parser) ParseUnaryExpr() {
func Precedence(tok int) int {
// TODO should use a map or array here for lookup
switch tok {
case Scanner.COR:
case Scanner.LOR:
return 1;
case Scanner.CAND:
case Scanner.LAND:
return 2;
case Scanner.EQL, Scanner.NEQ, Scanner.LSS, Scanner.LEQ, Scanner.GTR, Scanner.GEQ:
return 3;

67
usr/gri/src/scanner.go
View File

@ -16,7 +16,7 @@ export
SHL, SHR,
ADD_ASSIGN, SUB_ASSIGN, MUL_ASSIGN, QUO_ASSIGN, REM_ASSIGN,
AND_ASSIGN, OR_ASSIGN, XOR_ASSIGN, SHL_ASSIGN, SHR_ASSIGN,
CAND, COR,
LAND, LOR,
BREAK, CASE, CHAN, CONST, CONTINUE, DEFAULT, ELSE, EXPORT, FALLTHROUGH, FALSE,
FOR, FUNC, GO, GOTO, IF, IMPORT, INTERFACE, IOTA, MAP, NEW, NIL, PACKAGE, RANGE,
RETURN, SELECT, STRUCT, SWITCH, TRUE, TYPE, VAR
@ -81,8 +81,8 @@ const (
SHL_ASSIGN;
SHR_ASSIGN;
CAND;
COR;
LAND;
LOR;
// keywords
KEYWORDS_BEG;
@ -184,8 +184,8 @@ func TokenName(tok int) string {
case SHL_ASSIGN: return "<<=";
case SHR_ASSIGN: return ">>=";
case CAND: return "&&";
case COR: return "||";
case LAND: return "&&";
case LOR: return "||";
case BREAK: return "break";
case CASE: return "case";
@ -249,6 +249,10 @@ func digit_val (ch int) int {
export Scanner
type Scanner struct {
filename string; // error reporting only
nerrors int; // number of errors
errpos int; // last error position
src string;
pos int; // current reading position
ch int; // one char look-ahead
@ -389,17 +393,25 @@ func (S *Scanner) LineCol(pos int) (line, col int) {
func (S *Scanner) Error(pos int, msg string) {
line, col := S.LineCol(pos);
print "error ", line, ":", col, ": ", msg, "\n";
const errdist = 10;
if pos > S.errpos + errdist || S.nerrors == 0 {
line, col := S.LineCol(pos);
print S.filename, ":", line, ":", col, ": ", msg, "\n";
S.nerrors++;
S.errpos = pos;
}
}
func (S *Scanner) Open (src string) {
func (S *Scanner) Open (filename, src string) {
if Keywords == nil {
Init();
}
//S.nerrors = 0;
S.filename = filename;
S.nerrors = 0;
S.errpos = 0;
S.src = src;
S.pos = 0;
S.Next();
@ -438,19 +450,18 @@ func IntString(x, base int) string {
}
func CharString(ch int) string {
s := string(ch);
switch ch {
case '\a': s = "\\a";
case '\b': s = "\\b";
case '\f': s = "\\f";
case '\n': s = "\\n";
case '\r': s = "\\r";
case '\t': s = "\\t";
case '\v': s = "\\v";
case '\\': s = "\\";
case '\'': s = "\\'";
case '\a': s = `\a`;
case '\b': s = `\b`;
case '\f': s = `\f`;
case '\n': s = `\n`;
case '\r': s = `\r`;
case '\t': s = `\t`;
case '\v': s = `\v`;
case '\\': s = `\\`;
case '\'': s = `\'`;
}
return "'" + s + "' (U+" + IntString(ch, 16) + ")";
}
@ -708,11 +719,10 @@ func (S *Scanner) Select4 (tok0, tok1, ch2, tok2, tok3 int) int {
func (S *Scanner) Scan () (tok, beg, end int) {
S.SkipWhitespace();
tok = ILLEGAL;
beg = S.pos - 1;
end = beg;
ch := S.ch;
tok = ILLEGAL;
beg = S.chpos;
switch {
case is_letter(ch): tok = S.ScanIdentifier();
case digit_val(ch) < 10: tok = S.ScanNumber(false);
@ -755,12 +765,13 @@ func (S *Scanner) Scan () (tok, beg, end int) {
case '>': tok = S.Select4(GTR, GEQ, '>', SHR, SHR_ASSIGN);
case '=': tok = S.Select2(ASSIGN, EQL);
case '!': tok = S.Select2(NOT, NEQ);
case '&': tok = S.Select3(AND, AND_ASSIGN, '&', CAND);
case '|': tok = S.Select3(OR, OR_ASSIGN, '|', COR);
case '&': tok = S.Select3(AND, AND_ASSIGN, '&', LAND);
case '|': tok = S.Select3(OR, OR_ASSIGN, '|', LOR);
default:
S.Error(beg, "illegal character " + CharString(ch));
tok = ILLEGAL;
}
}
end = S.pos - 1; // TODO correct? (Unicode)
return tok, beg, end;
return tok, beg, S.chpos;
}

10
usr/gri/src/test_parser.go
View File

@ -8,9 +8,9 @@ import Scanner "scanner"
import Parser "parser"
func Parse(src string, verbose int) {
func Parse(filename, src string, verbose int) {
S := new(Scanner.Scanner);
S.Open(src);
S.Open(filename, src);
P := new(Parser.Parser);
P.Open(S, verbose);
@ -31,12 +31,10 @@ func main() {
continue;
}
var src string;
var ok bool;
src, ok = sys.readfile(sys.argv(i));
src, ok := sys.readfile(sys.argv(i));
if ok {
print "parsing " + sys.argv(i) + "\n";
Parse(src, verbose);
Parse(sys.argv(i), src, verbose);
} else {
print "error: cannot read " + sys.argv(i) + "\n";
}

11
usr/gri/src/test_scanner.go
View File

@ -7,14 +7,11 @@ package main
import Scanner "scanner"
func Scan(src string) {
func Scan(filename, src string) {
S := new(Scanner.Scanner);
S.Open(src);
S.Open(filename, src);
for {
//var t Scanner.Token;
var tok, beg, end int;
tok, beg, end = S.Scan(/*&t*/);
//t.Print(); // TODO this doesn't compile?
tok, beg, end := S.Scan();
print Scanner.TokenName(tok), "\t ", src[beg : end], "\n";
if tok == Scanner.EOF {
return;
@ -30,7 +27,7 @@ func main() {
src, ok = sys.readfile(sys.argv(i));
if ok {
print "scanning " + sys.argv(i) + "\n";
Scan(src);
Scan(sys.argv(i), src);
} else {
print "error: cannot read " + sys.argv(i) + "\n";
}