Builder,README: add feature for parse tracing

Builder/GoGenCode.go

@@ -27,11 +27,13 @@ type GoBuilder struct {
 	StateFunc  string
 	ReduceFunc string
 	Translate  string
+	// ReduceTrace funciton
+	ReduceTrace string
 }
 
 func NewGoBuilder(w *parser.Walker) *GoBuilder {
 	return &GoBuilder{
-		HeaderPart: `/*Generator Code , do not modify*/\n`,
+		HeaderPart: `/*Generator Code , do not modify*/\n import "strings"\n`,
 		vnode:      w.VistorNode.(*parser.RootVistor),
 	}
 }
@@ -49,6 +51,7 @@ func (b *GoBuilder) buildConstPart() {
 
 func (b *GoBuilder) buildUionAndCode() {
 	str := `
+var IsTrace bool = false
 var StateSymStack = []StateSym{}
 var StackPointer = 0
 type Context struct {
@@ -71,7 +74,7 @@ type StateSym struct {
 }`
 	str = fmt.Sprintf(str, b.vnode.GetUion())
 	b.UnionPart = str
-	b.CodeHeader = b.vnode.GetCode()
+	b.CodeHeader = b.vnode.GetCode() + "\n import \"strings\"\n"
 	b.CodeLast = b.vnode.GetCodeCopy()
 }
 
@@ -101,6 +104,7 @@ func (b *GoBuilder) buildStateFunc() {
 	b.StateFunc = `
 // Push StateSym
 func PushStateSym(state *StateSym) {
+	TraceShift(state)
 	if StackPointer >= len(StateSymStack) {
 		StateSymStack = append(StateSymStack, *state)
 	} else {
@@ -157,7 +161,8 @@ func Parser(input string) *ValType {
 		s := &StateSymStack[StackPointer-1]
 		a := s.Action(lookAhead)
 		if a == ERROR_ACTION {
-			panic("Grammar parse error")
+			lines := strings.Split(input[:currentPos], "\n")
+			panic("Grammar parse error near :" + lines[len(lines)-1])
 		} else if a == ACCEPT_ACTION {
 			return &s.ValType
 		} else {
@@ -175,6 +180,7 @@ func Parser(input string) *ValType {
 				s := &StateSymStack[StackPointer-1]
 				gotoState := s.Action(SymTy.YySymIndex)
 				SymTy.Yystate = gotoState
+				TraceReduce(reduceIndex, gotoState, TraceTranslate(lookAhead))
 				PushStateSym(SymTy)
 			}
 		}
@@ -205,6 +211,55 @@ func translate(c int) int {
 		}
 	}
 	b.Translate = fmt.Sprintf(str, caseCodes)
+	// build Trace info
+	traceFun := `
+func TraceShift(s *StateSym) {
+	if IsTrace {
+		fmt.Printf("Shift %%s, push state %%d\n", TraceTranslate(s.YySymIndex), s.Yystate)
+	}
+}
+func TraceTranslate(c int) string {
+	var conv string = ""
+	switch c {
+%s
+	}
+	return conv
+}
+
+`
+	caseCodes = ""
+	for _, sy := range b.vnode.G.Symbols {
+		caseCodes += fmt.Sprintf("\tcase %d:\n \tconv = \"%s\"\n", sy.ID, parser.RemoveTempName(sy.Name))
+	}
+	b.Translate += fmt.Sprintf(traceFun, caseCodes)
+}
+
+func (b *GoBuilder) buildReduceTrace() {
+	str := `
+func TraceReduce(reduceIndex, s int, look string) {
+	if IsTrace {
+		switch reduceIndex {
+%s
+		}
+	}
+}
+`
+
+	caseCode := ""
+	for i := 1; i < len(b.vnode.G.ProductoinRules); i++ {
+		caseCode += fmt.Sprintf("\t\tcase %d: \n", i)
+		oneRule := b.vnode.GetRules(i - 1)
+		leftPartString := "use Reduce:" + parser.RemoveTempName(oneRule.LeftPart.Name)
+		var rightPartString string = ""
+		for _, rightPart := range oneRule.RighPart {
+			rightPartString += parser.RemoveTempName(rightPart.Name) + " "
+		}
+		strTrace := fmt.Sprintf("%s -> %s",
+			leftPartString, rightPartString)
+		caseCode += fmt.Sprintf("\n\t\tfmt.Printf(\"look ahead %%s, %s, go to state %%d\\n\", look, s)\n", strTrace)
+	}
+	str = fmt.Sprintf(str, caseCode)
+	b.ReduceTrace = str
 }
 
 // make ReduceFunc
@@ -278,6 +333,7 @@ func GoGenFromString(input string, file string) error {
 	}
 
 	b.buildReduceFunc()
+	b.buildReduceTrace()
 	b.buildTranslate()
 	// Create file and write to it
 	f, err := os.Create(file)
@@ -292,6 +348,7 @@ func GoGenFromString(input string, file string) error {
 	f.WriteString(b.StateFunc)
 	f.WriteString(b.ReduceFunc)
 	f.WriteString(b.Translate)
+	f.WriteString(b.ReduceTrace)
 	f.Close()
 	return nil
 }

Builder/GoGenPackTableCode.go

@@ -34,6 +34,7 @@ func (b *GoBuilder) buildPackStateFunc() {
 	b.StateFunc = `
 // Push StateSym
 func PushStateSym(state *StateSym) {
+	TraceShift(state)
 	if StackPointer >= len(StateSymStack) {
 		StateSymStack = append(StateSymStack, *state)
 	} else {
@@ -94,7 +95,8 @@ func Parser(input string) *ValType {
 		s := &StateSymStack[StackPointer-1]
 		a := s.Action(lookAhead)
 		if a == ERROR_ACTION {
-			panic("Grammar parse error")
+			lines := strings.Split(input[:currentPos], "\n")
+			panic("Grammar parse error near :" + lines[len(lines)-1])
 		} else if a == ACCEPT_ACTION {
 			return &s.ValType
 		} else {
@@ -112,6 +114,7 @@ func Parser(input string) *ValType {
 				s := &StateSymStack[StackPointer-1]
 				gotoState := s.Action(SymTy.YySymIndex)
 				SymTy.Yystate = gotoState
+				TraceReduce(reduceIndex, gotoState, TraceTranslate(lookAhead))
 				PushStateSym(SymTy)
 			}
 		}

README.md

@@ -22,6 +22,37 @@ bin/yaccgo generate typescript examples/exprts.y expts.ts
 ```
 at your `y `file  You should do as follower
 more in [manual](./Docs/manual.md)
+
+# Trace
+After generate the parse code, modify the `var IsTrace bool = false` to `var IsTrace bool = true` , then you can see the trace of the parser. feature completed for go, other are WIP.
+for example:
+```
+bin/yaccgo generate go examples/ladd.y out/ladd.go
+```
+then you modify the ladd.go file, change code `var IsTrace bool = false` to `var IsTrace bool = true`, then
+```
+go run out/ladd.go
+```
+You can see trace information
+```
+look ahead NUM, use Reduce:PROG -> , go to state 1
+Shift PROG, push state 1
+Shift NUM, push state 3
+look ahead PLUS, use Reduce:E -> NUM , go to state 2
+Shift E, push state 2
+Shift PLUS, push state 5
+Shift NUM, push state 3
+look ahead NL, use Reduce:E -> NUM , go to state 6
+Shift E, push state 6
+look ahead NL, use Reduce:E -> E PLUS E , go to state 2
+Shift E, push state 2
+Shift NL, push state 4
+3
+look ahead $, use Reduce:PROG -> PROG E NL , go to state 1
+Shift PROG, push state 1
+0
+```
+
 # Design
 
 LALR1 Algorithm Base on