//ParseGrammar parses a relapse grammar and returns an abstract syntax tree.
func (this *Parser) ParseGrammar(s string) (*ast.Grammar, error) {
scanner := lexer.NewLexer([]byte(s))
g, err := this.Parse(scanner)
if err != nil {
return nil, err
}
gram, ok := g.(*ast.Grammar)
if !ok {
return nil, &errWrongType{"*relapse.Grammar", g}
}
return gram, nil
}
//ParseExpr returns a parsed expression or error, given a string.
func (this *Parser) ParseExpr(s string) (res *ast.Expr, err error) {
scanner := lexer.NewLexer([]byte(s))
g, err := this.Parse(scanner)
if err != nil {
return nil, err
}
gram, ok := g.(*ast.Grammar)
if !ok {
return nil, &errWrongType{"*relapse.Grammar", g}
}
if len(gram.GetPatternDecls()) != 0 {
return nil, &errWrongType{"found pattern declarations where none were expected", g}
}
if gram.GetTopPattern().LeafNode == nil {
return nil, &errWrongType{"LeafNode == nil", g}
}
return gram.GetTopPattern().GetLeafNode().GetExpr(), nil
}