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Diffstat (limited to 'driver/parser.go')
-rw-r--r--driver/parser.go264
1 files changed, 31 insertions, 233 deletions
diff --git a/driver/parser.go b/driver/parser.go
index 59fb56a..1e7af29 100644
--- a/driver/parser.go
+++ b/driver/parser.go
@@ -8,49 +8,6 @@ import (
"github.com/nihei9/vartan/spec"
)
-type Node struct {
- KindName string
- Text string
- Row int
- Col int
- Children []*Node
-}
-
-func PrintTree(w io.Writer, node *Node) {
- printTree(w, node, "", "")
-}
-
-func printTree(w io.Writer, node *Node, ruledLine string, childRuledLinePrefix string) {
- if node == nil {
- return
- }
-
- if node.Text != "" {
- fmt.Fprintf(w, "%v%v %#v\n", ruledLine, node.KindName, node.Text)
- } else {
- fmt.Fprintf(w, "%v%v\n", ruledLine, node.KindName)
- }
-
- num := len(node.Children)
- for i, child := range node.Children {
- var line string
- if num > 1 && i < num-1 {
- line = "├─ "
- } else {
- line = "└─ "
- }
-
- var prefix string
- if i >= num-1 {
- prefix = " "
- } else {
- prefix = "│ "
- }
-
- printTree(w, child, childRuledLinePrefix+line, childRuledLinePrefix+prefix)
- }
-}
-
type SyntaxError struct {
Row int
Col int
@@ -61,20 +18,6 @@ type SyntaxError struct {
type ParserOption func(p *Parser) error
-func MakeAST() ParserOption {
- return func(p *Parser) error {
- p.makeAST = true
- return nil
- }
-}
-
-func MakeCST() ParserOption {
- return func(p *Parser) error {
- p.makeCST = true
- return nil
- }
-}
-
// DisableLAC disables LAC (lookahead correction). When the grammar has the LALR class, LAC is enabled by default.
func DisableLAC() ParserOption {
return func(p *Parser) error {
@@ -83,21 +26,18 @@ func DisableLAC() ParserOption {
}
}
-type semanticFrame struct {
- cst *Node
- ast *Node
+func SemanticAction(semAct SemanticActionSet) ParserOption {
+ return func(p *Parser) error {
+ p.semAct = semAct
+ return nil
+ }
}
type Parser struct {
gram *spec.CompiledGrammar
lex *mldriver.Lexer
stateStack *stateStack
- semStack []*semanticFrame
- cst *Node
- ast *Node
- makeAST bool
- makeCST bool
- needSemAct bool
+ semAct SemanticActionSet
disableLAC bool
onError bool
shiftCount int
@@ -127,8 +67,6 @@ func NewParser(gram *spec.CompiledGrammar, src io.Reader, opts ...ParserOption)
}
}
- p.needSemAct = p.makeAST || p.makeCST
-
return p, nil
}
@@ -159,7 +97,9 @@ ACTION_LOOP:
p.shift(nextState)
- p.actOnShift(tok)
+ if p.semAct != nil {
+ p.semAct.Shift(tok)
+ }
tok, err = p.nextToken()
if err != nil {
@@ -175,12 +115,16 @@ ACTION_LOOP:
accepted := p.reduce(prodNum)
if accepted {
- p.actOnAccepting()
+ if p.semAct != nil {
+ p.semAct.Accept()
+ }
return nil
}
- p.actOnReduction(prodNum)
+ if p.semAct != nil {
+ p.semAct.Reduce(prodNum)
+ }
default: // Error
if p.onError {
tok, err = p.nextToken()
@@ -202,10 +146,17 @@ ACTION_LOOP:
ExpectedTerminals: p.searchLookahead(p.stateStack.top()),
})
- ok := p.trapError()
+ count, ok := p.trapError()
if !ok {
+ if p.semAct != nil {
+ p.semAct.MissError()
+ }
+
return nil
}
+ if p.semAct != nil {
+ p.semAct.TrapError(count)
+ }
p.onError = true
p.shiftCount = 0
@@ -217,7 +168,9 @@ ACTION_LOOP:
p.shift(act * -1)
- p.actOnError()
+ if p.semAct != nil {
+ p.semAct.ShiftError()
+ }
}
}
}
@@ -321,177 +274,22 @@ func (p *Parser) reduce(prodNum int) bool {
return false
}
-func (p *Parser) trapError() bool {
+func (p *Parser) trapError() (int, bool) {
+ count := 0
for {
if p.gram.ParsingTable.ErrorTrapperStates[p.stateStack.top()] != 0 {
- return true
+ return count, true
}
if p.stateStack.top() != p.gram.ParsingTable.InitialState {
p.stateStack.pop(1)
- p.semStack = p.semStack[:len(p.semStack)-1]
+ count++
} else {
- return false
+ return 0, false
}
}
}
-func (p *Parser) actOnShift(tok *mldriver.Token) {
- if !p.needSemAct {
- return
- }
-
- term := p.tokenToTerminal(tok)
-
- var ast *Node
- var cst *Node
- if p.makeAST {
- ast = &Node{
- KindName: p.gram.ParsingTable.Terminals[term],
- Text: tok.Text(),
- Row: tok.Row,
- Col: tok.Col,
- }
- }
- if p.makeCST {
- cst = &Node{
- KindName: p.gram.ParsingTable.Terminals[term],
- Text: tok.Text(),
- Row: tok.Row,
- Col: tok.Col,
- }
- }
-
- p.semStack = append(p.semStack, &semanticFrame{
- cst: cst,
- ast: ast,
- })
-}
-
-func (p *Parser) actOnReduction(prodNum int) {
- if !p.needSemAct {
- return
- }
-
- lhs := p.gram.ParsingTable.LHSSymbols[prodNum]
-
- // When an alternative is empty, `n` will be 0, and `handle` will be empty slice.
- n := p.gram.ParsingTable.AlternativeSymbolCounts[prodNum]
- handle := p.semStack[len(p.semStack)-n:]
-
- var ast *Node
- var cst *Node
- if p.makeAST {
- act := p.gram.ASTAction.Entries[prodNum]
- var children []*Node
- if act != nil {
- // Count the number of children in advance to avoid frequent growth in a slice for children.
- {
- l := 0
- for _, e := range act {
- if e > 0 {
- l++
- } else {
- offset := e*-1 - 1
- l += len(handle[offset].ast.Children)
- }
- }
-
- children = make([]*Node, l)
- }
-
- p := 0
- for _, e := range act {
- if e > 0 {
- offset := e - 1
- children[p] = handle[offset].ast
- p++
- } else {
- offset := e*-1 - 1
- for _, c := range handle[offset].ast.Children {
- children[p] = c
- p++
- }
- }
- }
- } else {
- // If an alternative has no AST action, a driver generates
- // a node with the same structure as a CST.
-
- children = make([]*Node, len(handle))
- for i, f := range handle {
- children[i] = f.ast
- }
- }
-
- ast = &Node{
- KindName: p.gram.ParsingTable.NonTerminals[lhs],
- Children: children,
- }
- }
- if p.makeCST {
- children := make([]*Node, len(handle))
- for i, f := range handle {
- children[i] = f.cst
- }
-
- cst = &Node{
- KindName: p.gram.ParsingTable.NonTerminals[lhs],
- Children: children,
- }
- }
-
- p.semStack = p.semStack[:len(p.semStack)-n]
- p.semStack = append(p.semStack, &semanticFrame{
- cst: cst,
- ast: ast,
- })
-}
-
-func (p *Parser) actOnAccepting() {
- if !p.needSemAct {
- return
- }
-
- top := p.semStack[len(p.semStack)-1]
- p.cst = top.cst
- p.ast = top.ast
-}
-
-func (p *Parser) actOnError() {
- if !p.needSemAct {
- return
- }
-
- errSym := p.gram.ParsingTable.ErrorSymbol
-
- var ast *Node
- var cst *Node
- if p.makeAST {
- ast = &Node{
- KindName: p.gram.ParsingTable.Terminals[errSym],
- }
- }
- if p.makeCST {
- cst = &Node{
- KindName: p.gram.ParsingTable.Terminals[errSym],
- }
- }
-
- p.semStack = append(p.semStack, &semanticFrame{
- cst: cst,
- ast: ast,
- })
-}
-
-func (p *Parser) CST() *Node {
- return p.cst
-}
-
-func (p *Parser) AST() *Node {
- return p.ast
-}
-
func (p *Parser) SyntaxErrors() []*SyntaxError {
return p.synErrs
}
generated by cgit v1.2.3 (git 2.49.0) at 2025-07-13 20:41:50 +0000