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Diffstat (limited to 'ruby_2_2/lib/racc/rdoc/grammar.en.rdoc')
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diff --git a/ruby_2_2/lib/racc/rdoc/grammar.en.rdoc b/ruby_2_2/lib/racc/rdoc/grammar.en.rdoc deleted file mode 100644 index a154246ee5..0000000000 --- a/ruby_2_2/lib/racc/rdoc/grammar.en.rdoc +++ /dev/null @@ -1,219 +0,0 @@ -= Racc Grammar File Reference - -== Global Structure - -== Class Block and User Code Block - -There are two blocks on toplevel. One is 'class' block, another is 'user code' -block. 'user code' block MUST be placed after 'class' block. - -== Comments - -You can insert comments about all places. Two style comments can be used, Ruby style '#.....' and C style '/\*......*\/'. - -== Class Block - -The class block is formed like this: - - class CLASS_NAME - [precedance table] - [token declarations] - [expected number of S/R conflicts] - [options] - [semantic value convertion] - [start rule] - rule - GRAMMARS - -CLASS_NAME is a name of parser class. This is the name of generating parser -class. - -If CLASS_NAME includes '::', Racc outputs module clause. For example, writing -"class M::C" causes creating the code bellow: - - module M - class C - : - : - end - end - -== Grammar Block - -The grammar block describes grammar which is able to be understood by parser. -Syntax is: - - (token): (token) (token) (token).... (action) - - (token): (token) (token) (token).... (action) - | (token) (token) (token).... (action) - | (token) (token) (token).... (action) - -(action) is an action which is executed when its (token)s are found. -(action) is a ruby code block, which is surrounded by braces: - - { print val[0] - puts val[1] } - -Note that you cannot use '%' string, here document, '%r' regexp in action. - -Actions can be omitted. When it is omitted, '' (empty string) is used. - -A return value of action is a value of left side value ($$). It is value of -result, or returned value by `return` statement. - -Here is an example of whole grammar block. - - rule - goal: definition rules source { result = val } - - definition: /* none */ { result = [] } - | definition startdesig { result[0] = val[1] } - | definition - precrule # this line continues from upper line - { - result[1] = val[1] - } - - startdesig: START TOKEN - -You can use the following special local variables in action: - -* result ($$) - -The value of left-hand side (lhs). A default value is val[0]. - -* val ($1,$2,$3...) - -An array of value of right-hand side (rhs). - -* _values (...$-2,$-1,$0) - -A stack of values. DO NOT MODIFY this stack unless you know what you are doing. - -== Operator Precedence - -This function is equal to '%prec' in yacc. -To designate this block: - - prechigh - nonassoc '++' - left '*' '/' - left '+' '-' - right '=' - preclow - -`right` is yacc's %right, `left` is yacc's %left. - -`=` + (symbol) means yacc's %prec: - - prechigh - nonassoc UMINUS - left '*' '/' - left '+' '-' - preclow - - rule - exp: exp '*' exp - | exp '-' exp - | '-' exp =UMINUS # equals to "%prec UMINUS" - : - : - -== expect - -Racc has bison's "expect" directive. - - # Example - - class MyParser - rule - expect 3 - : - : - -This directive declares "expected" number of shift/reduce conflicts. If -"expected" number is equal to real number of conflicts, Racc does not print -conflict warning message. - -== Declaring Tokens - -By declaring tokens, you can avoid many meaningless bugs. If declared token -does not exist or existing token does not decleared, Racc output warnings. -Declaration syntax is: - - token TOKEN_NAME AND_IS_THIS - ALSO_THIS_IS AGAIN_AND_AGAIN THIS_IS_LAST - -== Options - -You can write options for Racc command in your Racc file. - - options OPTION OPTION ... - -Options are: - -* omit_action_call - -omits empty action call or not. - -* result_var - -uses local variable "result" or not. - -You can use 'no_' prefix to invert their meanings. - -== Converting Token Symbol - -Token symbols are, as default, - - * naked token string in Racc file (TOK, XFILE, this_is_token, ...) - --> symbol (:TOK, :XFILE, :this_is_token, ...) - * quoted string (':', '.', '(', ...) - --> same string (':', '.', '(', ...) - -You can change this default by "convert" block. -Here is an example: - - convert - PLUS 'PlusClass' # We use PlusClass for symbol of `PLUS' - MIN 'MinusClass' # We use MinusClass for symbol of `MIN' - end - -We can use almost all ruby value can be used by token symbol, -except 'false' and 'nil'. These cause unexpected parse error. - -If you want to use String as token symbol, special care is required. -For example: - - convert - class '"cls"' # in code, "cls" - PLUS '"plus\n"' # in code, "plus\n" - MIN "\"minus#{val}\"" # in code, \"minus#{val}\" - end - -== Start Rule - -'%start' in yacc. This changes start rule. - - start real_target - -== User Code Block - -"User Code Block" is a Ruby source code which is copied to output. There are -three user code blocks, "header" "inner" and "footer". - -Format of user code is like this: - - ---- header - ruby statement - ruby statement - ruby statement - - ---- inner - ruby statement - : - : - -If four '-' exist on line head, Racc treat it as beginning of user code block. -The name of user code block must be one word. |