Address audit issues

Eliminate changes which implemented the '-tflag' command line switch, as being unnecessary, along with the API change to the Lex and Error methods.

Author: danswartzendruber

cmd/goyacc/doc.go

@@ -66,32 +66,44 @@ symbols, including types, the parser, and the lexer, generated and
 referenced by yacc's generated code.  Setting it to distinct values
 allows multiple grammars to be placed in a single package.
 
-If the -t flag is specified, goyacc will generate a parser compatible
-with bison's token location tracking semantics.  For more details:
+goyacc will generate a parser compatible with bison's token location
+tracking semantics.  For more details:
 
 https://www.gnu.org/software/bison/manual/html_node/Tracking-Locations.html
 https://www.gnu.org/software/bison/manual/html_node/Token-Locations.html
 
-If this flag is specified, the Lex and Error methods in the Lexer
-interface definition change as follows:
+The generated Go parser will define two types:
 
-type yyLexer interface {
-        Lex(lval *yySymType, loc *YYLTYPE) int
-        Error(loc *YYLTYPE, s string)
+type yyPos struct {
+        line   int
+        column int
 }
 
-where YYLTYPE is defined as:
-
-type YYLTYPE struct {
-        firstLine   int
-        firstColumn int
-        lastLine    int
-        lastColumn  int
+type yySymLoc struct {
+        pos yyPos
+        end yyPos
 }
 
-The token tracking structure is stashed inside the yySymType structure.
-This simplifies the changes, since yacc already has to copy the structure
-in question.
+The pos field refers to the beginning of the token in question,
+and the end field to the end it.  To avoid having to change the
+definition of the lexer's Error method, just before the parser calls
+the Error method, it will set a global variable, yyErrLoc to the
+address of the problematic token's yySymLoc structure.  Since the
+lexer provides location information to the parser, and in turn is
+provided it, if needed, it's up to the lexer to do so consistently.
+
+As in the above-cited BISON web pages, goyacc will support the use
+of @N, where N is an integer from 1 to 9, and will be expanded in
+the generated parser to the appropriate variable. If an action rule
+wants to print a specific error message, the lexer should be written
+to provide one to the parser.
+
+If goyacc was invoked with an explicit prefix, via the '-p' switch,
+the above types and variables will have the appropriate prefix.
+
+The token tracking structure yySymLoc is stored inside the yySymType
+structure.  This simplifies the changes, since goyacc already has to
+copy the structure in question.
 
 */
 package main

cmd/goyacc/yacc.go

@@ -156,7 +156,6 @@ var foutput *bufio.Writer   // y.output file
 
 var fmtImported bool // output file has recorded an import of "fmt"
 
-var tflag bool    // -t - enable Bison style token location tracking
 var oflag string  // -o [y.go]		- y.go file
 var vflag string  // -v [y.output]	- y.output file
 var lflag bool    // -l			- disable line directives
@@ -167,7 +166,6 @@ func init() {
 	flag.StringVar(&prefix, "p", "yy", "name prefix to use in generated code")
 	flag.StringVar(&vflag, "v", "y.output", "create parsing tables")
 	flag.BoolVar(&lflag, "l", false, "disable line directives")
-	flag.BoolVar(&tflag, "t", false, "enable token location tracking")
 }
 
 var initialstacksize = 16
@@ -386,25 +384,7 @@ func setup() {
 		fmt.Fprintf(stderr, "yacc: stack size too small\n")
 		usage()
 	}
-	yaccpar = yaccpartext
-	if tflag {
-		lexMethStr := fmt.Sprintf("Lex(lval *$$SymType, loc *%sLTYPE)",
-			strings.ToUpper(prefix))
-		yaccpar = strings.Replace(yaccpar, "Lex(lval *$$SymType)",
-			lexMethStr, 1)
-		errMethStr := fmt.Sprintf("Error(loc *%sLTYPE, s string)",
-			strings.ToUpper(prefix))
-		yaccpar = strings.Replace(yaccpar, "Error(s string)", errMethStr, 1)
-		yaccpar = strings.Replace(yaccpar, "lex.Error(",
-			"lex.Error(&$$rcvr.lval.$$lloc, ", 1)
-		lexMethStr = fmt.Sprintf("lex.Lex(lval, &lval.$$lloc)")
-		yaccpar = strings.Replace(yaccpar, "lex.Lex(lval)", lexMethStr, 1)
-	} else {
-		yaccpar = strings.Replace(yaccpar, "$$VAL.$$lloc.firstColumn = $$S[$$p+1].$$lloc.firstColumn", "", 1)
-		yaccpar = strings.Replace(yaccpar, "$$VAL.$$lloc.lastColumn = $$S[$$pt].$$lloc.lastColumn", "", 1)
-	}
-	yaccpar = strings.ReplaceAll(yaccpar, "$$", prefix)
-
+	yaccpar = strings.ReplaceAll(yaccpartext, "$$", prefix)
 	openup()
 
 	fmt.Fprintf(ftable, "// Code generated by goyacc %s. DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))
@@ -1072,15 +1052,15 @@ func chfind(t int, s string) int {
 // copy the union declaration to the output, and the define file if present
 //
 func cpyunion() {
-	if tflag {
-		fmt.Fprintf(ftable, "\ntype %sLTYPE struct {",
-			strings.ToUpper(prefix))
-		fmt.Fprintf(ftable, "\n\tfirstLine int")
-		fmt.Fprintf(ftable, "\n\tfirstColumn int")
-		fmt.Fprintf(ftable, "\n\tlastLine int")
-		fmt.Fprintf(ftable, "\n\tlastColumn int")
-		fmt.Fprintf(ftable, "\n}\n")
-	}
+	fmt.Fprintf(ftable, "\ntype %sPos struct {", prefix)
+	fmt.Fprintf(ftable, "\n\tline\tint")
+	fmt.Fprintf(ftable, "\n\tcolumn\tint")
+	fmt.Fprintf(ftable, "\n}\n")
+
+	fmt.Fprintf(ftable, "\ntype %sSymLoc struct {", prefix)
+	fmt.Fprintf(ftable, "\n\tpos %sPos", prefix)
+	fmt.Fprintf(ftable, "\n\tend %sPos", prefix)
+	fmt.Fprintf(ftable, "\n}\n")
 
 	if !lflag {
 		fmt.Fprintf(ftable, "\n//line %v:%v\n", infile, lineno)
@@ -1101,11 +1081,8 @@ out:
 			lineno++
 		case '{':
 			if level == 0 {
-				fmt.Fprintf(ftable, "\n\tyys int")
-				if tflag {
-					fmt.Fprintf(ftable, "\n\t%slloc %sLTYPE", prefix,
-						strings.ToUpper(prefix))
-				}
+				fmt.Fprintf(ftable, "\n\tyys\tint")
+				fmt.Fprintf(ftable, "\n\tsymLoc\t%sSymLoc", prefix)
 			}
 			level++
 		case '}':
@@ -1329,13 +1306,10 @@ loop:
 			brac++
 
 		case '@':
-			if !tflag {
-				errorf("@ not valid without -tflag!")
-			}
 			c2 := getrune(finput)
 			if isdigit(c2) {
-				fmt.Fprintf(fcode, "%sDollar[%d].%slloc",
-					prefix, int(c2-'0'), prefix)
+				fmt.Fprintf(fcode, "%sDollar[%d].symLoc",
+					prefix, int(c2-'0'))
 				continue loop
 			} else {
 				errorf("unexpected @")
@@ -3313,6 +3287,7 @@ var yaccpartext = `
 var (
 	$$Debug        = 0
 	$$ErrorVerbose = false
+	$$ErrLoc *$$SymLoc
 )
 
 type $$Lexer interface {
@@ -3559,6 +3534,7 @@ $$default:
 		/* error ... attempt to resume parsing */
 		switch Errflag {
 		case 0: /* brand new error */
+            		$$ErrLoc = &$$rcvr.lval.symLoc
 			$$lex.Error($$ErrorMessage($$state, $$token))
 			Nerrs++
 			if $$Debug >= 1 {
@@ -3621,8 +3597,10 @@ $$default:
 	}
 	$$VAL = $$S[$$p+1]
 
-    $$VAL.$$lloc.firstColumn = $$S[$$p+1].$$lloc.firstColumn
-    $$VAL.$$lloc.lastColumn = $$S[$$pt].$$lloc.lastColumn
+	$$VAL.symLoc.pos.line = $$S[$$p+1].symLoc.pos.line
+	$$VAL.symLoc.pos.column = $$S[$$p+1].symLoc.pos.column
+	$$VAL.symLoc.end.line = $$S[$$pt].symLoc.end.line
+	$$VAL.symLoc.end.column = $$S[$$pt].symLoc.end.column
 
 	/* consult goto table to find next state */
 	$$n = $$R1[$$n]