diff options
Diffstat (limited to 'grammar/grammar.go')
| -rw-r--r-- | grammar/grammar.go | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/grammar/grammar.go b/grammar/grammar.go index c5b8a0c..b405429 100644 --- a/grammar/grammar.go +++ b/grammar/grammar.go @@ -752,10 +752,11 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd continue LOOP_RHS } offsets[elem.Label.Name] = i - } else { - if elem.ID != "" { - offsets[elem.ID] = i - } + } + // A symbol having a label can be specified by both the label and the symbol name. + // So record the symbol's position, whether or not it has a label. + if elem.ID != "" { + offsets[elem.ID] = i } } @@ -829,6 +830,7 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd continue LOOP_RHS } astAct := make([]*astActionEntry, len(dir.Parameters)) + consumedOffsets := map[int]struct{}{} for i, param := range dir.Parameters { if param.ID == "" { b.errs = append(b.errs, &verr.SpecError{ @@ -850,6 +852,16 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd }) continue LOOP_RHS } + if _, consumed := consumedOffsets[offset]; consumed { + b.errs = append(b.errs, &verr.SpecError{ + Cause: semErrDuplicateElem, + Detail: param.ID, + Row: param.Pos.Row, + Col: param.Pos.Col, + }) + continue LOOP_RHS + } + consumedOffsets[offset] = struct{}{} if param.Expansion { elem := alt.Elements[offset] |