diff options
Diffstat (limited to 'grammar/grammar.go')
| -rw-r--r-- | grammar/grammar.go | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/grammar/grammar.go b/grammar/grammar.go index 4507ddd..e7271c0 100644 --- a/grammar/grammar.go +++ b/grammar/grammar.go @@ -10,6 +10,7 @@ import ( type Grammar struct { lexSpec *mlspec.LexSpec + skipLexKinds []mlspec.LexKind productionSet *productionSet augmentedStartSymbol symbol symbolTable *symbolTable @@ -19,6 +20,7 @@ func NewGrammar(root *spec.RootNode) (*Grammar, error) { symTab := newSymbolTable() anonPat2Sym := map[string]symbol{} var lexSpec *mlspec.LexSpec + var skip []mlspec.LexKind { entries := []*mlspec.LexEntry{} anonPats := []string{} @@ -51,6 +53,11 @@ func NewGrammar(root *spec.RootNode) (*Grammar, error) { if alt.Action != nil { act := alt.Action switch act.Name { + case "skip": + if act.Parameter != "" { + return nil, fmt.Errorf("action 'skip' needs no parameter") + } + skip = append(skip, mlspec.LexKind(prod.LHS)) case "push": if act.Parameter == "" { return nil, fmt.Errorf("action 'push' needs a parameter") @@ -186,6 +193,7 @@ func NewGrammar(root *spec.RootNode) (*Grammar, error) { return &Grammar{ lexSpec: lexSpec, + skipLexKinds: skip, productionSet: prods, augmentedStartSymbol: augStartSym, symbolTable: symTab, @@ -206,24 +214,37 @@ func Compile(gram *Grammar) (*spec.CompiledGrammar, error) { } kind2Term := make([][]int, len(lexSpec.Modes)) + skip := make([][]int, len(lexSpec.Modes)) for modeNum, spec := range lexSpec.Specs { if modeNum == 0 { kind2Term[0] = nil + skip[0] = nil continue } - rec := make([]int, len(spec.Kinds)) + + k2tRec := make([]int, len(spec.Kinds)) + skipRec := make([]int, len(spec.Kinds)) for n, k := range spec.Kinds { if n == 0 { - rec[0] = symbolNil.num().Int() + k2tRec[0] = symbolNil.num().Int() continue } + sym, ok := gram.symbolTable.toSymbol(k.String()) if !ok { return nil, fmt.Errorf("terminal symbol '%v' (in '%v' mode) is not found in a symbol table", k, lexSpec.Modes[modeNum]) } - rec[n] = sym.num().Int() + k2tRec[n] = sym.num().Int() + + for _, sk := range gram.skipLexKinds { + if k != sk { + continue + } + skipRec[n] = 1 + } } - kind2Term[modeNum] = rec + kind2Term[modeNum] = k2tRec + skip[modeNum] = skipRec } terms, err := gram.symbolTable.getTerminalTexts() @@ -278,6 +299,7 @@ func Compile(gram *Grammar) (*spec.CompiledGrammar, error) { Maleeni: &spec.Maleeni{ Spec: lexSpec, KindToTerminal: kind2Term, + Skip: skip, }, }, ParsingTable: &spec.ParsingTable{ |