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FIQL (Feed Item Query Language) parser and query build

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fiqlex src fiql_lexer.xrl
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src/fiql_lexer.xrl 

Definitions.



SELECTOR                = [0-9a-zA-Z:._]+

ARG_TXT                 = [^\s\t\n\r"';,=!\(\)]+

ARG_DOUBLE_QUOTED_TXT   = "([^"\\]|(\\"))+"

ARG_SINGLE_QUOTED_TXT   = '([^'\\]|(\\'))+'

ARG_INT                 = (\+|-)?[0-9]+

ARG_FLOAT               = (\+|-)?[0-9]+\.[0-9]+((E|e)(\+|-)?[0-9]+)?

ARG_BOOL                = ((t|T)(r|R)(u|U)(e|E))|((f|F)(a|A)(l|L)(s|S)(e|E))

COMPARISON              = =[0-9a-z]+=

WHITESPACE              = [\s\t\n\r]



Rules.



{ARG_FLOAT}             : {token, {arg_float, TokenLine, list_to_float(TokenChars)}}.

{ARG_INT}               : {token, {arg_int, TokenLine, list_to_integer(TokenChars)}}.

{ARG_BOOL}              : {token, {arg_bool, TokenLine, list_to_bool(TokenChars)}}.

{SELECTOR}              : {token, {selector, TokenLine, TokenChars}}.

{ARG_TXT}               : {token, {value, TokenLine, TokenChars}}.

{ARG_DOUBLE_QUOTED_TXT} : {token, {value, TokenLine, from_double_quoted(TokenChars)}}.

{ARG_SINGLE_QUOTED_TXT} : {token, {value, TokenLine, from_single_quoted(TokenChars)}}.

{COMPARISON}            : {token, {comparison,  TokenLine, strip_equals(TokenChars)}}.

\(                      : {token, {'(',  TokenLine}}.

\)                      : {token, {')',  TokenLine}}.

\,                      : {token, {or_op,  TokenLine}}.

\;                      : {token, {and_op,  TokenLine}}.

==                      : {token, {equal,  TokenLine}}.

!=                      : {token, {not_equal,  TokenLine}}.

{WHITESPACE}+           : skip_token.



Erlang code.



to_bool(<<"true">>) ->

  true;

to_bool(<<"false">>) ->

  false.



list_to_bool(Chars) ->

  to_bool(string:lowercase(list_to_binary(Chars))).



from_double_quoted(Chars) ->

  binary_to_list(re:replace(string:slice(list_to_binary(Chars), 1, string:length(list_to_binary(Chars))-2), "\\\\\"", "\"", [global, {return, binary}])).



from_single_quoted(Chars) ->

  binary_to_list(re:replace(string:slice(list_to_binary(Chars), 1, string:length(list_to_binary(Chars))-2), "\\\\'", "'", [global, {return, binary}])).



strip_equals(Chars) ->

  binary_to_list(string:slice(list_to_binary(Chars), 1, string:length(list_to_binary(Chars))-2)).