diff options
Diffstat (limited to 'grammar/symbol.go')
| -rw-r--r-- | grammar/symbol.go | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/grammar/symbol.go b/grammar/symbol.go index ee58737..6e357bb 100644 --- a/grammar/symbol.go +++ b/grammar/symbol.go @@ -60,6 +60,9 @@ const ( symbolStart = symbol(maskNonTerminal | maskStartOrEOF | symbolNumStart) // 0100 0000 0000 0001 symbolEOF = symbol(maskTerminal | maskStartOrEOF | symbolNumEOF) // 1100 0000 0000 0001: The EOF symbol is treated as a terminal symbol. + // The symbol name contains `<` and `>` to avoid conflicting with user-defined symbols. + symbolNameEOF = "<eof>" + nonTerminalNumMin = symbolNum(2) // The number 1 is used by a start symbol. terminalNumMin = symbolNum(2) // The number 1 is used by the EOF symbol. symbolNumMax = symbolNum(0xffff) >> 2 // 0011 1111 1111 1111 @@ -161,11 +164,15 @@ type symbolTable struct { func newSymbolTable() *symbolTable { return &symbolTable{ - text2Sym: map[string]symbol{}, - sym2Text: map[symbol]string{}, + text2Sym: map[string]symbol{ + symbolNameEOF: symbolEOF, + }, + sym2Text: map[symbol]string{ + symbolEOF: symbolNameEOF, + }, termTexts: []string{ - "", // Nil - "", // EOF + "", // Nil + symbolNameEOF, // EOF }, nonTermTexts: []string{ "", // Nil @@ -228,7 +235,7 @@ func (t *symbolTable) toText(sym symbol) (string, bool) { func (t *symbolTable) terminalSymbols() []symbol { syms := make([]symbol, 0, t.termNum.Int()-terminalNumMin.Int()) for sym := range t.sym2Text { - if !sym.isTerminal() || sym.isNil() || sym.isEOF() { + if !sym.isTerminal() || sym.isNil() { continue } syms = append(syms, sym) |