Pass a token that caused a syntax error to the semantic action APIs

3 files changed, 17 insertions, 16 deletions

diff --git a/driver/parser.go b/driver/parser.go
index 3099d73..c9b6229 100644
--- a/driver/parser.go
+++ b/driver/parser.go
@@ -137,7 +137,7 @@ ACTION_LOOP:
 				}
 				if tok.EOF {
 					if p.semAct != nil {
-						p.semAct.MissError()
+						p.semAct.MissError(tok)
 					}
 
 					return nil
@@ -157,7 +157,7 @@ ACTION_LOOP:
 			count, ok := p.trapError()
 			if !ok {
 				if p.semAct != nil {
-					p.semAct.MissError()
+					p.semAct.MissError(tok)
 				}
 
 				return nil
@@ -174,7 +174,7 @@ ACTION_LOOP:
 			p.shift(act * -1)
 
 			if p.semAct != nil {
-				p.semAct.TrapAndShiftError(count)
+				p.semAct.TrapAndShiftError(tok, count)
 			}
 		}
 	}
diff --git a/driver/semantic_action.go b/driver/semantic_action.go
index 5bec385..1db703b 100644
--- a/driver/semantic_action.go
+++ b/driver/semantic_action.go
@@ -22,13 +22,14 @@ type SemanticActionSet interface {
 	Accept()
 
 	// TrapAndShiftError runs when the driver traps a syntax error and shifts a error symbol onto the state stack.
-	// `n` is the number of frames that the driver discards from the state stack.
-	// Unlike `Shift` function, this function doesn't take a token as an argument because a token corresponding to
-	// the error symbol doesn't exist.
-	TrapAndShiftError(n int)
-
-	// MissError runs when the driver fails to trap a syntax error.
-	MissError()
+	// `cause` is a token that caused a syntax error. `popped` is the number of frames that the driver discards
+	// from the state stack.
+	// Unlike `Shift` function, this function doesn't take a token to be shifted as an argument because a token
+	// corresponding to the error symbol doesn't exist.
+	TrapAndShiftError(cause *mldriver.Token, popped int)
+
+	// MissError runs when the driver fails to trap a syntax error. `cause` is a token that caused a syntax error.
+	MissError(cause *mldriver.Token)
 }
 
 var _ SemanticActionSet = &SyntaxTreeActionSet{}
@@ -204,8 +205,8 @@ func (a *SyntaxTreeActionSet) Accept() {
 	a.ast = top[0].ast
 }
 
-func (a *SyntaxTreeActionSet) TrapAndShiftError(n int) {
-	a.semStack.pop(n)
+func (a *SyntaxTreeActionSet) TrapAndShiftError(cause *mldriver.Token, popped int) {
+	a.semStack.pop(popped)
 
 	errSym := a.gram.ParsingTable.ErrorSymbol
 
@@ -228,7 +229,7 @@ func (a *SyntaxTreeActionSet) TrapAndShiftError(n int) {
 	})
 }
 
-func (a *SyntaxTreeActionSet) MissError() {
+func (a *SyntaxTreeActionSet) MissError(cause *mldriver.Token) {
 }
 
 func (a *SyntaxTreeActionSet) CST() *Node {
diff --git a/driver/semantic_action_test.go b/driver/semantic_action_test.go
index c3f8943..1d785e4 100644
--- a/driver/semantic_action_test.go
+++ b/driver/semantic_action_test.go
@@ -37,11 +37,11 @@ func (a *testSemAct) Accept() {
 	a.actLog = append(a.actLog, "accept")
 }
 
-func (a *testSemAct) TrapAndShiftError(n int) {
-	a.actLog = append(a.actLog, fmt.Sprintf("trap/%v/shift/error", n))
+func (a *testSemAct) TrapAndShiftError(cause *mldriver.Token, popped int) {
+	a.actLog = append(a.actLog, fmt.Sprintf("trap/%v/shift/error", popped))
 }
 
-func (a *testSemAct) MissError() {
+func (a *testSemAct) MissError(cause *mldriver.Token) {
 	a.actLog = append(a.actLog, "miss")
 }