Hi guys,
I am testing to parse relational expressions and defined the following
relational operators:
rule(:gt_op) { str('>') >> space? }
rule(:ge_op) { str('<=') >> space? }
rule(:lt_op) { str('<') >> space? }
rule(:le_op) { str('<=') >> space? }
rule(:eq_op) { str('==') >> space? }
To test them I used the following parse statements:
Parser.new.rel_operation.parse_with_debug(' ( a - b ) < c ')
=> Parsing succeds
Parser.new.rel_operation.parse_with_debug(' ( a + b ) > c ')
=> Parsing succeeds
Parser.new.rel_operation.parse_with_debug(' ( a + b ) == c' )
=> Parsing succeeds
Parser.new.rel_operation.parse_with_debug(' ( a + b ) >= c' )
=> Parsing does NOT succeeds
Parser.new.rel_operation.parse_with_debug(' ( a + b ) <= c' )
=> Parsing does NOT succeeds
Because of the parsing failures of the '>=' and '<=' operators I
replaced the relational operator '>=' with ':=' just to know if Parslet
could parse those two tokens as a relational operator.
Parser.new.rel_operation.parse_with_debug(' ( a + b ) := c' )
=> Parsing DOES succeeds!
Can anyone explain why parsing with e.g. '==', '<', '>' and ':=' went
well and '>=' and '<=' does not.
Is there an 'undocumented' feature ;-) in Parslet which does not
allow using '>=' and '<=' as symbols in Parslet or did I made a mistake?
Thanks in advance,
Thiel
