formula_peg.txt in rubyfromexcel-0.0.9

- old
+ new
@@ -1,24 +1,24 @@
 formula                         := space? expression+
-expression                       = string_join | arithmetic | comparison | thing
+expression                       = string_join | comparison | arithmetic | thing
 thing                            = function | brackets | any_reference | string | percentage | number | boolean | prefix | named_reference 
 argument                         = expression | null
 function                        := /[A-Z]+/ `'(' space argument? (space `',' space argument)* space `')'
 brackets                        := `'(' space expression+ space `')'
 string_join                     := thing (space `"&" space thing)+
 arithmetic                      := thing (space operator space thing)+
-comparison                      := thing space comparator space thing
+comparison                      := (arithmetic | thing) space comparator space (arithmetic | thing)
 comparator                      := '>=' | '<=' | '<>' | '>' | '<' | '='
 string                          := `'"' /[^"]*/ `'"'
 any_reference                    = external_reference | any_internal_reference
 any_internal_reference           = table_reference | local_table_reference | quoted_sheet_reference | sheet_reference | sheetless_reference
 percentage                      := /[-+]?[0-9]+\.?[0-9]*/ `'%'
 number                          := /[-+]?[0-9]+\.?[0-9]*([eE][-+]?[0-9]+)?/
 operator                        := '+' | '-' | '/' | '*' | '^'
 external_reference              := /\[\d+\]!?/ any_internal_reference
 table_reference                 := table_name `'[' (range_structured_reference | complex_structured_reference | simple_structured_reference) `']'
 local_table_reference           := `'[' (range_structured_reference | complex_structured_reference | overly_structured_reference | simple_structured_reference) `']'
-table_name                       = /[.a-zA-Z0-9]+/
+table_name                       = /[.a-zA-Z0-9_]+/
 range_structured_reference       = /\[[^\u005d]*\],\[[^\u005d]*\]:\[[^\u005d]*\]/
 complex_structured_reference     = /\[[^\u005d]*\],\[[^\u005d]*\]/
 overly_structured_reference      = `'[' simple_structured_reference `']'
 simple_structured_reference      = /[^\u005d]*/
 named_reference                 := /[#a-zA-Z][\w_.!]+/