Bug #9429 ยป 0001-lib-racc-rdoc-grammar.en.rdoc-Doc-Fix-typos.patch
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== Class Block and User Code Block
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There's two block on toplevel.
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one is 'class' block, another is 'user code' block. 'user code' block MUST
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places after 'class' block.
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There are two blocks on toplevel. One is 'class' block, another is 'user code'
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block. 'user code' block MUST be placed after 'class' block.
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== Comment
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== Comments
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You can insert comment about all places. Two style comment can be used,
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Ruby style (#.....) and C style (/*......*/) .
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You can insert comments about all places. Two style comments can be used, Ruby style '#.....' and C style '/\*......*\/'.
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== Class Block
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| ... | ... | |
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class CLASS_NAME
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[precedance table]
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[token declearations]
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[expected number of S/R conflict]
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[token declarations]
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[expected number of S/R conflicts]
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[options]
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[semantic value convertion]
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[start rule]
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rule
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GRAMMARS
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CLASS_NAME is a name of parser class.
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This is the name of generating parser class.
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CLASS_NAME is a name of parser class. This is the name of generating parser
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class.
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If CLASS_NAME includes '::', Racc outputs module clause.
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For example, writing "class M::C" causes creating the code bellow:
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If CLASS_NAME includes '::', Racc outputs module clause. For example, writing
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"class M::C" causes creating the code bellow:
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module M
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class C
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| ... | ... | |
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== Grammar Block
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The grammar block discripts grammar which is able
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to be understood by parser. Syntax is:
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The grammar block describes grammar which is able to be understood by parser.
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Syntax is:
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(token): (token) (token) (token).... (action)
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Note that you cannot use '%' string, here document, '%r' regexp in action.
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Actions can be omitted.
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When it is omitted, '' (empty string) is used.
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Actions can be omitted. When it is omitted, '' (empty string) is used.
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A return value of action is a value of left side value ($$).
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It is value of result, or returned value by "return" statement.
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A return value of action is a value of left side value ($$). It is value of
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result, or returned value by `return` statement.
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Here is an example of whole grammar block.
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rule
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goal: definition ruls source { result = val }
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goal: definition rules source { result = val }
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definition: /* none */ { result = [] }
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| definition startdesig { result[0] = val[1] }
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| definition
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precrule # this line continue from upper line
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precrule # this line continues from upper line
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{
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result[1] = val[1]
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}
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startdesig: START TOKEN
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You can use following special local variables in action.
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You can use the following special local variables in action:
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* result ($$)
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| ... | ... | |
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* _values (...$-2,$-1,$0)
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A stack of values.
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DO NOT MODIFY this stack unless you know what you are doing.
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A stack of values. DO NOT MODIFY this stack unless you know what you are doing.
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== Operator Precedence
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right '='
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preclow
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`right' is yacc's %right, `left' is yacc's %left.
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`right` is yacc's %right, `left` is yacc's %left.
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`=' + (symbol) means yacc's %prec:
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`=` + (symbol) means yacc's %prec:
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prechigh
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nonassoc UMINUS
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:
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:
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This directive declears "expected" number of shift/reduce conflict.
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If "expected" number is equal to real number of conflicts,
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racc does not print confliction warning message.
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This directive declares "expected" number of shift/reduce conflicts. If
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"expected" number is equal to real number of conflicts, Racc does not print
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conflict warning message.
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== Declaring Tokens
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By declaring tokens, you can avoid many meanless bugs.
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If decleared token does not exist/existing token does not decleared,
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Racc output warnings. Declearation syntax is:
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By declaring tokens, you can avoid many meaningless bugs. If declared token
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does not exist or existing token does not decleared, Racc output warnings.
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Declaration syntax is:
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token TOKEN_NAME AND_IS_THIS
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ALSO_THIS_IS AGAIN_AND_AGAIN THIS_IS_LAST
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== Options
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You can write options for racc command in your racc file.
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You can write options for Racc command in your Racc file.
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options OPTION OPTION ...
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* omit_action_call
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omit empty action call or not.
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omits empty action call or not.
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* result_var
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use/does not use local variable "result"
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uses local variable "result" or not.
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You can use 'no_' prefix to invert its meanings.
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You can use 'no_' prefix to invert their meanings.
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== Converting Token Symbol
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Token symbols are, as default,
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* naked token string in racc file (TOK, XFILE, this_is_token, ...)
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* naked token string in Racc file (TOK, XFILE, this_is_token, ...)
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--> symbol (:TOK, :XFILE, :this_is_token, ...)
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* quoted string (':', '.', '(', ...)
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--> same string (':', '.', '(', ...)
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| ... | ... | |
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end
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We can use almost all ruby value can be used by token symbol,
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except 'false' and 'nil'. These are causes unexpected parse error.
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except 'false' and 'nil'. These causes unexpected parse error.
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If you want to use String as token symbol, special care is required.
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For example:
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start real_target
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This statement will not be used forever, I think.
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== User Code Block
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"User Code Block" is a Ruby source code which is copied to output.
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There are three user code block, "header" "inner" and "footer".
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"User Code Block" is a Ruby source code which is copied to output. There are
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three user code blocks, "header" "inner" and "footer".
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Format of user code is like this:
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:
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:
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If four '-' exist on line head,
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racc treat it as beginning of user code block.
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A name of user code must be one word.
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If four '-' exist on line head, Racc treat it as beginning of user code block.
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The name of user code block must be one word.
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