{:error, {:undefined, :standard_syntax_parser, ['syntax error before: ', []]}}

Question

So I am trying to use yecc.

Terminals string string_delimeter.

Nonterminals value string_content.

Rootsymbol value.

value -> string : extract_value('$1').

value -> string_delimeter string_content string_delimeter : '$2'.
string_content -> value string_content : ['$1' | '$2'].
string_content -> value : '$1'.

Erlang code.

extract_value({_, Value}) -> Value.

For the input:

[string_delimeter: '\'', string: 'test', string_delimeter: '\'']

I get

{:error, {:undefined, :standard_syntax_parser, ['syntax error before: ', []]}}

If I delete any (left or right) string_delimeter surrounding string_content:

value -> string_delimeter string_content string_delimeter : '$2'.

value -> string_delimeter string_content : '$2'.

for

[string_delimeter: '\'', string: 'test']

it returns

{:ok, 'test'}

I don't really understand this behaviour, where is the issue?

Answer 1

I did not figure why this is a problem in yecc: token_1 token_2 token_1 I really wish I would know, but I have a way around this:

Terminals string string_delimeter whitespace.


Nonterminals value string_content.


Rootsymbol value.

value -> string : extract_value('$1').

value -> string_delimeter string_content : '$2'.
string_content -> string_content string_delimeter : '$1'.
string_content -> value whitespace string_content : ['$1' | '$3'].
string_content -> value : ['$1'].

Erlang code.

extract_value({_, Value}) -> Value.