diff options
Diffstat (limited to 'src/pkg/ebnf/ebnf.go')
| -rw-r--r-- | src/pkg/ebnf/ebnf.go | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/src/pkg/ebnf/ebnf.go b/src/pkg/ebnf/ebnf.go index 7918c4593..661afdd35 100644 --- a/src/pkg/ebnf/ebnf.go +++ b/src/pkg/ebnf/ebnf.go @@ -5,10 +5,10 @@ // Package ebnf is a library for EBNF grammars. The input is text ([]byte) // satisfying the following grammar (represented itself in EBNF): // -// Production = name "=" Expression "." . +// Production = name "=" [ Expression ] "." . // Expression = Alternative { "|" Alternative } . // Alternative = Term { Term } . -// Term = name | token [ "..." token ] | Group | Option | Repetition . +// Term = name | token [ "…" token ] | Group | Option | Repetition . // Group = "(" Expression ")" . // Option = "[" Expression "]" . // Repetition = "{" Expression "}" . @@ -82,6 +82,12 @@ type ( Body Expression // {body} } + // A Bad node stands for pieces of source code that lead to a parse error. + Bad struct { + TokPos token.Pos + Error string // parser error message + } + // A Production node represents an EBNF production. Production struct { Name *Name @@ -103,6 +109,7 @@ func (x *Range) Pos() token.Pos { return x.Begin.Pos() } func (x *Group) Pos() token.Pos { return x.Lparen } func (x *Option) Pos() token.Pos { return x.Lbrack } func (x *Repetition) Pos() token.Pos { return x.Lbrace } +func (x *Bad) Pos() token.Pos { return x.TokPos } func (x *Production) Pos() token.Pos { return x.Name.Pos() } |