X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/f6b561d9f9cbc6fc95bbb86518372a5cb52f45a6..c6b1772473d0a26faa22464df98718d0d0ae2e2e:/doc/bison.texi diff --git a/doc/bison.texi b/doc/bison.texi index d18167fa..1c4bfd4e 100644 --- a/doc/bison.texi +++ b/doc/bison.texi @@ -280,6 +280,7 @@ Operator Precedence * Precedence Only:: How to specify precedence only. * Precedence Examples:: How these features are used in the previous example. * How Precedence:: How they work. +* Non Operators:: Using precedence for general conflicts. Tuning LR @@ -298,6 +299,8 @@ Handling Context Dependencies Debugging Your Parser * Understanding:: Understanding the structure of your parser. +* Graphviz:: Getting a visual representation of the parser. +* Xml:: Getting a markup representation of the parser. * Tracing:: Tracing the execution of your parser. Tracing Your Parser @@ -5479,7 +5482,7 @@ The parser namespace is @code{foo} and @code{yylex} is referenced as @findex %define api.location.type @itemize @bullet -@item Language(s): C++ +@item Language(s): C++, Java @item Purpose: Define the location type. @xref{User Defined Location Type}. @@ -5546,9 +5549,33 @@ More user feedback will help to stabilize it.) -@c ================================================== api.tokens.prefix -@item api.tokens.prefix -@findex %define api.tokens.prefix +@c ================================================== api.token.constructor +@item api.token.constructor +@findex %define api.token.constructor + +@itemize @bullet +@item Language(s): +C++ + +@item Purpose: +When variant-based semantic values are enabled (@pxref{C++ Variants}), +request that symbols be handled as a whole (type, value, and possibly +location) in the scanner. @xref{Complete Symbols}, for details. + +@item Accepted Values: +Boolean. + +@item Default Value: +@code{false} +@item History: +introduced in Bison 2.8 +@end itemize +@c api.token.constructor + + +@c ================================================== api.token.prefix +@item api.token.prefix +@findex %define api.token.prefix @itemize @item Languages(s): all @@ -5559,7 +5586,7 @@ target language. For instance @example %token FILE for ERROR -%define api.tokens.prefix "TOK_" +%define api.token.prefix "TOK_" %% start: FILE for ERROR; @end example @@ -5580,36 +5607,16 @@ letters, underscores, and ---not at the beginning--- digits). @item Default Value: empty +@item History: +introduced in Bison 2.8 @end itemize -@c api.tokens.prefix - - -@c ================================================== lex_symbol -@item lex_symbol -@findex %define lex_symbol - -@itemize @bullet -@item Language(s): -C++ - -@item Purpose: -When variant-based semantic values are enabled (@pxref{C++ Variants}), -request that symbols be handled as a whole (type, value, and possibly -location) in the scanner. @xref{Complete Symbols}, for details. - -@item Accepted Values: -Boolean. - -@item Default Value: -@code{false} -@end itemize -@c lex_symbol +@c api.token.prefix -@c ================================================== lr.default-reductions +@c ================================================== lr.default-reduction -@item lr.default-reductions -@findex %define lr.default-reductions +@item lr.default-reduction +@findex %define lr.default-reduction @itemize @bullet @item Language(s): all @@ -5625,12 +5632,15 @@ feedback will help to stabilize it.) @item @code{accepting} if @code{lr.type} is @code{canonical-lr}. @item @code{most} otherwise. @end itemize +@item History: +introduced as @code{lr.default-reduction} in 2.5, renamed as +@code{lr.default-reduction} in 2.8. @end itemize -@c ============================================ lr.keep-unreachable-states +@c ============================================ lr.keep-unreachable-state -@item lr.keep-unreachable-states -@findex %define lr.keep-unreachable-states +@item lr.keep-unreachable-state +@findex %define lr.keep-unreachable-state @itemize @bullet @item Language(s): all @@ -5639,7 +5649,10 @@ remain in the parser tables. @xref{Unreachable States}. @item Accepted Values: Boolean @item Default Value: @code{false} @end itemize -@c lr.keep-unreachable-states +introduced as @code{lr.keep_unreachable_states} in 2.3b, renamed as +@code{lr.keep-unreachable-state} in 2.5, and as +@code{lr.keep-unreachable-state} in 2.8. +@c lr.keep-unreachable-state @c ================================================== lr.type @@ -6863,7 +6876,7 @@ expr: term: '(' expr ')' | term '!' -| NUMBER +| "number" ; @end group @end example @@ -6902,20 +6915,20 @@ statements, with a pair of rules like this: @example @group if_stmt: - IF expr THEN stmt -| IF expr THEN stmt ELSE stmt + "if" expr "then" stmt +| "if" expr "then" stmt "else" stmt ; @end group @end example @noindent -Here we assume that @code{IF}, @code{THEN} and @code{ELSE} are -terminal symbols for specific keyword tokens. +Here @code{"if"}, @code{"then"} and @code{"else"} are terminal symbols for +specific keyword tokens. -When the @code{ELSE} token is read and becomes the lookahead token, the +When the @code{"else"} token is read and becomes the lookahead token, the contents of the stack (assuming the input is valid) are just right for reduction by the first rule. But it is also legitimate to shift the -@code{ELSE}, because that would lead to eventual reduction by the second +@code{"else"}, because that would lead to eventual reduction by the second rule. This situation, where either a shift or a reduction would be valid, is @@ -6924,14 +6937,14 @@ these conflicts by choosing to shift, unless otherwise directed by operator precedence declarations. To see the reason for this, let's contrast it with the other alternative. -Since the parser prefers to shift the @code{ELSE}, the result is to attach +Since the parser prefers to shift the @code{"else"}, the result is to attach the else-clause to the innermost if-statement, making these two inputs equivalent: @example -if x then if y then win (); else lose; +if x then if y then win; else lose; -if x then do; if y then win (); else lose; end; +if x then do; if y then win; else lose; end; @end example But if the parser chose to reduce when possible rather than shift, the @@ -6939,9 +6952,9 @@ result would be to attach the else-clause to the outermost if-statement, making these two inputs equivalent: @example -if x then if y then win (); else lose; +if x then if y then win; else lose; -if x then do; if y then win (); end; else lose; +if x then do; if y then win; end; else lose; @end example The conflict exists because the grammar as written is ambiguous: either @@ -6954,11 +6967,16 @@ This particular ambiguity was first encountered in the specifications of Algol 60 and is called the ``dangling @code{else}'' ambiguity. To avoid warnings from Bison about predictable, legitimate shift/reduce -conflicts, use the @code{%expect @var{n}} declaration. +conflicts, you can use the @code{%expect @var{n}} declaration. There will be no warning as long as the number of shift/reduce conflicts is exactly @var{n}, and Bison will report an error if there is a different number. -@xref{Expect Decl, ,Suppressing Conflict Warnings}. +@xref{Expect Decl, ,Suppressing Conflict Warnings}. However, we don't +recommend the use of @code{%expect} (except @samp{%expect 0}!), as an equal +number of conflicts does not mean that they are the @emph{same}. When +possible, you should rather use precedence directives to @emph{fix} the +conflicts explicitly (@pxref{Non Operators,, Using Precedence For Non +Operators}). The definition of @code{if_stmt} above is solely to blame for the conflict, but the conflict does not actually appear without additional @@ -6967,7 +6985,6 @@ the conflict: @example @group -%token IF THEN ELSE variable %% @end group @group @@ -6979,13 +6996,13 @@ stmt: @group if_stmt: - IF expr THEN stmt -| IF expr THEN stmt ELSE stmt + "if" expr "then" stmt +| "if" expr "then" stmt "else" stmt ; @end group expr: - variable + "identifier" ; @end example @@ -7005,6 +7022,7 @@ shift and when to reduce. * Precedence Only:: How to specify precedence only. * Precedence Examples:: How these features are used in the previous example. * How Precedence:: How they work. +* Non Operators:: Using precedence for general conflicts. @end menu @node Why Precedence @@ -7143,16 +7161,11 @@ would declare them in groups of equal precedence. For example, @code{'+'} is declared with @code{'-'}: @example -%left '<' '>' '=' NE LE GE +%left '<' '>' '=' "!=" "<=" ">=" %left '+' '-' %left '*' '/' @end example -@noindent -(Here @code{NE} and so on stand for the operators for ``not equal'' -and so on. We assume that these tokens are more than one character long -and therefore are represented by names, not character literals.) - @node How Precedence @subsection How Precedence Works @@ -7175,6 +7188,44 @@ resolved. Not all rules and not all tokens have precedence. If either the rule or the lookahead token has no precedence, then the default is to shift. +@node Non Operators +@subsection Using Precedence For Non Operators + +Using properly precedence and associativity directives can help fixing +shift/reduce conflicts that do not involve arithmetics-like operators. For +instance, the ``dangling @code{else}'' problem (@pxref{Shift/Reduce, , +Shift/Reduce Conflicts}) can be solved elegantly in two different ways. + +In the present case, the conflict is between the token @code{"else"} willing +to be shifted, and the rule @samp{if_stmt: "if" expr "then" stmt}, asking +for reduction. By default, the precedence of a rule is that of its last +token, here @code{"then"}, so the conflict will be solved appropriately +by giving @code{"else"} a precedence higher than that of @code{"then"}, for +instance as follows: + +@example +@group +%nonassoc "then" +%nonassoc "else" +@end group +@end example + +Alternatively, you may give both tokens the same precedence, in which case +associativity is used to solve the conflict. To preserve the shift action, +use right associativity: + +@example +%right "then" "else" +@end example + +Neither solution is perfect however. Since Bison does not provide, so far, +support for ``scoped'' precedence, both force you to declare the precedence +of these keywords with respect to the other operators your grammar. +Therefore, instead of being warned about new conflicts you would be unaware +of (e.g., a shift/reduce conflict due to @samp{if test then 1 else 2 + 3} +being ambiguous: @samp{if test then 1 else (2 + 3)} or @samp{(if test then 1 +else 2) + 3}?), the conflict will be already ``fixed''. + @node Contextual Precedence @section Context-Dependent Precedence @cindex context-dependent precedence @@ -7335,30 +7386,38 @@ reduce/reduce conflict must be studied and usually eliminated. Here is the proper way to define @code{sequence}: @example +@group sequence: /* empty */ @{ printf ("empty sequence\n"); @} | sequence word @{ printf ("added word %s\n", $2); @} ; +@end group @end example Here is another common error that yields a reduce/reduce conflict: @example sequence: +@group /* empty */ | sequence words | sequence redirects ; +@end group +@group words: /* empty */ | words word ; +@end group +@group redirects: /* empty */ | redirects redirect ; +@end group @end example @noindent @@ -7411,6 +7470,58 @@ redirects: @end group @end example +Yet this proposal introduces another kind of ambiguity! The input +@samp{word word} can be parsed as a single @code{words} composed of two +@samp{word}s, or as two one-@code{word} @code{words} (and likewise for +@code{redirect}/@code{redirects}). However this ambiguity is now a +shift/reduce conflict, and therefore it can now be addressed with precedence +directives. + +To simplify the matter, we will proceed with @code{word} and @code{redirect} +being tokens: @code{"word"} and @code{"redirect"}. + +To prefer the longest @code{words}, the conflict between the token +@code{"word"} and the rule @samp{sequence: sequence words} must be resolved +as a shift. To this end, we use the same techniques as exposed above, see +@ref{Non Operators,, Using Precedence For Non Operators}. One solution +relies on precedences: use @code{%prec} to give a lower precedence to the +rule: + +@example +%nonassoc "word" +%nonassoc "sequence" +%% +@group +sequence: + /* empty */ +| sequence word %prec "sequence" +| sequence redirect %prec "sequence" +; +@end group + +@group +words: + word +| words "word" +; +@end group +@end example + +Another solution relies on associativity: provide both the token and the +rule with the same precedence, but make them right-associative: + +@example +%right "word" "redirect" +%% +@group +sequence: + /* empty */ +| sequence word %prec "word" +| sequence redirect %prec "redirect" +; +@end group +@end example + @node Mysterious Conflicts @section Mysterious Conflicts @cindex Mysterious Conflicts @@ -7420,8 +7531,6 @@ Here is an example: @example @group -%token ID - %% def: param_spec return_spec ','; param_spec: @@ -7436,10 +7545,10 @@ return_spec: ; @end group @group -type: ID; +type: "id"; @end group @group -name: ID; +name: "id"; name_list: name | name ',' name_list @@ -7447,16 +7556,16 @@ name_list: @end group @end example -It would seem that this grammar can be parsed with only a single token -of lookahead: when a @code{param_spec} is being read, an @code{ID} is -a @code{name} if a comma or colon follows, or a @code{type} if another -@code{ID} follows. In other words, this grammar is LR(1). +It would seem that this grammar can be parsed with only a single token of +lookahead: when a @code{param_spec} is being read, an @code{"id"} is a +@code{name} if a comma or colon follows, or a @code{type} if another +@code{"id"} follows. In other words, this grammar is LR(1). @cindex LR @cindex LALR However, for historical reasons, Bison cannot by default handle all LR(1) grammars. -In this grammar, two contexts, that after an @code{ID} at the beginning +In this grammar, two contexts, that after an @code{"id"} at the beginning of a @code{param_spec} and likewise at the beginning of a @code{return_spec}, are similar enough that Bison assumes they are the same. @@ -7487,27 +7596,24 @@ distinct. In the above example, adding one rule to @example @group -%token BOGUS -@dots{} -%% @dots{} return_spec: type | name ':' type -| ID BOGUS /* This rule is never used. */ +| "id" "bogus" /* This rule is never used. */ ; @end group @end example This corrects the problem because it introduces the possibility of an -additional active rule in the context after the @code{ID} at the beginning of +additional active rule in the context after the @code{"id"} at the beginning of @code{return_spec}. This rule is not active in the corresponding context in a @code{param_spec}, so the two contexts receive distinct parser states. -As long as the token @code{BOGUS} is never generated by @code{yylex}, +As long as the token @code{"bogus"} is never generated by @code{yylex}, the added rule cannot alter the way actual input is parsed. In this particular example, there is another way to solve the problem: -rewrite the rule for @code{return_spec} to use @code{ID} directly +rewrite the rule for @code{return_spec} to use @code{"id"} directly instead of via @code{name}. This also causes the two confusing contexts to have different sets of active rules, because the one for @code{return_spec} activates the altered rule for @code{return_spec} @@ -7520,7 +7626,7 @@ param_spec: ; return_spec: type -| ID ':' type +| "id" ':' type ; @end example @@ -7683,7 +7789,7 @@ and the benefits of IELR, @pxref{Bibliography,,Denny 2008 March}, and @node Default Reductions @subsection Default Reductions @cindex default reductions -@findex %define lr.default-reductions +@findex %define lr.default-reduction @findex %nonassoc After parser table construction, Bison identifies the reduction with the @@ -7765,9 +7871,9 @@ token for which there is a conflict. The correct action in this case is to split the parse instead. To adjust which states have default reductions enabled, use the -@code{%define lr.default-reductions} directive. +@code{%define lr.default-reduction} directive. -@deffn {Directive} {%define lr.default-reductions @var{WHERE}} +@deffn {Directive} {%define lr.default-reduction @var{WHERE}} Specify the kind of states that are permitted to contain default reductions. The accepted values of @var{WHERE} are: @itemize @@ -7890,7 +7996,7 @@ parser community for years, for the publication that introduces LAC, @node Unreachable States @subsection Unreachable States -@findex %define lr.keep-unreachable-states +@findex %define lr.keep-unreachable-state @cindex unreachable states If there exists no sequence of transitions from the parser's start state to @@ -7903,7 +8009,7 @@ resolution because they are useless in the generated parser. However, keeping unreachable states is sometimes useful when trying to understand the relationship between the parser and the grammar. -@deffn {Directive} {%define lr.keep-unreachable-states @var{VALUE}} +@deffn {Directive} {%define lr.keep-unreachable-state @var{VALUE}} Request that Bison allow unreachable states to remain in the parser tables. @var{VALUE} must be a Boolean. The default is @code{false}. @end deffn @@ -8414,6 +8520,8 @@ automaton, and how to enable and understand the parser run-time traces. @menu * Understanding:: Understanding the structure of your parser. +* Graphviz:: Getting a visual representation of the parser. +* Xml:: Getting a markup representation of the parser. * Tracing:: Tracing the execution of your parser. @end menu @@ -8830,6 +8938,165 @@ precedence of @samp{/} with respect to @samp{+}, @samp{-}, and @samp{*}, but also because the associativity of @samp{/} is not specified. +Note that Bison may also produce an HTML version of this output, via an XML +file and XSLT processing (@pxref{Xml}). + +@c ================================================= Graphical Representation + +@node Graphviz +@section Visualizing Your Parser +@cindex dot + +As another means to gain better understanding of the shift/reduce +automaton corresponding to the Bison parser, a DOT file can be generated. Note +that debugging a real grammar with this is tedious at best, and impractical +most of the times, because the generated files are huge (the generation of +a PDF or PNG file from it will take very long, and more often than not it will +fail due to memory exhaustion). This option was rather designed for beginners, +to help them understand LR parsers. + +This file is generated when the @option{--graph} option is specified +(@pxref{Invocation, , Invoking Bison}). Its name is made by removing +@samp{.tab.c} or @samp{.c} from the parser implementation file name, and +adding @samp{.dot} instead. If the grammar file is @file{foo.y}, the +Graphviz output file is called @file{foo.dot}. + +The following grammar file, @file{rr.y}, will be used in the sequel: + +@example +%% +@group +exp: a ";" | b "."; +a: "0"; +b: "0"; +@end group +@end example + +The graphical output is very similar to the textual one, and as such it is +easier understood by making direct comparisons between them. See +@ref{Debugging, , Debugging Your Parser} for a detailled analysis of the +textual report. + +@subheading Graphical Representation of States + +The items (pointed rules) for each state are grouped together in graph nodes. +Their numbering is the same as in the verbose file. See the following points, +about transitions, for examples + +When invoked with @option{--report=lookaheads}, the lookahead tokens, when +needed, are shown next to the relevant rule between square brackets as a +comma separated list. This is the case in the figure for the representation of +reductions, below. + +@sp 1 + +The transitions are represented as directed edges between the current and +the target states. + +@subheading Graphical Representation of Shifts + +Shifts are shown as solid arrows, labelled with the lookahead token for that +shift. The following describes a reduction in the @file{rr.output} file: + +@example +@group +state 3 + + 1 exp: a . ";" + + ";" shift, and go to state 6 +@end group +@end example + +A Graphviz rendering of this portion of the graph could be: + +@center @image{figs/example-shift, 100pt} + +@subheading Graphical Representation of Reductions + +Reductions are shown as solid arrows, leading to a diamond-shaped node +bearing the number of the reduction rule. The arrow is labelled with the +appropriate comma separated lookahead tokens. If the reduction is the default +action for the given state, there is no such label. + +This is how reductions are represented in the verbose file @file{rr.output}: +@example +state 1 + + 3 a: "0" . [";"] + 4 b: "0" . ["."] + + "." reduce using rule 4 (b) + $default reduce using rule 3 (a) +@end example + +A Graphviz rendering of this portion of the graph could be: + +@center @image{figs/example-reduce, 120pt} + +When unresolved conflicts are present, because in deterministic parsing +a single decision can be made, Bison can arbitrarily choose to disable a +reduction, see @ref{Shift/Reduce, , Shift/Reduce Conflicts}. Discarded actions +are distinguished by a red filling color on these nodes, just like how they are +reported between square brackets in the verbose file. + +The reduction corresponding to the rule number 0 is the acceptation state. It +is shown as a blue diamond, labelled "Acc". + +@subheading Graphical representation of go tos + +The @samp{go to} jump transitions are represented as dotted lines bearing +the name of the rule being jumped to. + +Note that a DOT file may also be produced via an XML file and XSLT +processing (@pxref{Xml}). + +@c ================================================= XML + +@node Xml +@section Visualizing your parser in multiple formats +@cindex xml + +Bison supports two major report formats: textual output +(@pxref{Understanding}) when invoked with option @option{--verbose}, and DOT +(@pxref{Graphviz}) when invoked with option @option{--graph}. However, +another alternative is to output an XML file that may then be, with +@command{xsltproc}, rendered as either a raw text format equivalent to the +verbose file, or as an HTML version of the same file, with clickable +transitions, or even as a DOT. The @file{.output} and DOT files obtained via +XSLT have no difference whatsoever with those obtained by invoking +@command{bison} with options @option{--verbose} or @option{--graph}. + +The textual file is generated when the options @option{-x} or +@option{--xml[=FILE]} are specified, see @ref{Invocation,,Invoking Bison}. +If not specified, its name is made by removing @samp{.tab.c} or @samp{.c} +from the parser implementation file name, and adding @samp{.xml} instead. +For instance, if the grammar file is @file{foo.y}, the default XML output +file is @file{foo.xml}. + +Bison ships with a @file{data/xslt} directory, containing XSL Transformation +files to apply to the XML file. Their names are non-ambiguous: + +@table @file +@item xml2dot.xsl +Used to output a copy of the DOT visualization of the automaton. +@item xml2text.xsl +Used to output a copy of the .output file. +@item xml2xhtml.xsl +Used to output an xhtml enhancement of the .output file. +@end table + +Sample usage (requires @code{xsltproc}): +@example +$ bison -x input.y +@group +$ bison --print-datadir +/usr/local/share/bison +@end group +$ xsltproc /usr/local/share/bison/xslt/xml2xhtml.xsl input.xml > input.html +@end example + +@c ================================================= Tracing @node Tracing @section Tracing Your Parser @@ -9915,7 +10182,7 @@ to generate the @file{master/position.hh} and @file{master/location.hh} files, reused by other parsers as follows: @example -%define location_type "master::location" +%define api.location.type "master::location" %code requires @{ #include @} @end example @@ -10076,7 +10343,8 @@ or @node Complete Symbols @subsubsection Complete Symbols -If you specified both @code{%define variant} and @code{%define lex_symbol}, +If you specified both @code{%define variant} and +@code{%define api.token.constructor}, the @code{parser} class also defines the class @code{parser::symbol_type} which defines a @emph{complete} symbol, aggregating its type (i.e., the traditional value returned by @code{yylex}), its semantic value (i.e., the @@ -10098,7 +10366,7 @@ So for each token type, Bison generates named constructors as follows. @deftypemethod {symbol_type} {} make_@var{token} (const @var{value_type}& @var{value}, const location_type& @var{location}) @deftypemethodx {symbol_type} {} make_@var{token} (const location_type& @var{location}) Build a complete terminal symbol for the token type @var{token} (not -including the @code{api.tokens.prefix}) whose possible semantic value is +including the @code{api.token.prefix}) whose possible semantic value is @var{value} of adequate @var{value_type}. If location tracking is enabled, also pass the @var{location}. @end deftypemethod @@ -10106,7 +10374,7 @@ also pass the @var{location}. For instance, given the following declarations: @example -%define api.tokens.prefix "TOK_" +%define api.token.prefix "TOK_" %token IDENTIFIER; %token INTEGER; %token COLON; @@ -10338,18 +10606,18 @@ the grammar for. @end example @noindent +@findex %define api.token.constructor @findex %define variant -@findex %define lex_symbol This example will use genuine C++ objects as semantic values, therefore, we require the variant-based interface. To make sure we properly use it, we enable assertions. To fully benefit from type-safety and more natural -definition of ``symbol'', we enable @code{lex_symbol}. +definition of ``symbol'', we enable @code{api.token.constructor}. @comment file: calc++-parser.yy @example -%define variant +%define api.token.constructor %define parse.assert -%define lex_symbol +%define variant @end example @noindent @@ -10428,11 +10696,11 @@ The token numbered as 0 corresponds to end of file; the following line allows for nicer error messages referring to ``end of file'' instead of ``$end''. Similarly user friendly names are provided for each symbol. To avoid name clashes in the generated files (@pxref{Calc++ Scanner}), prefix -tokens with @code{TOK_} (@pxref{%define Summary,,api.tokens.prefix}). +tokens with @code{TOK_} (@pxref{%define Summary,,api.token.prefix}). @comment file: calc++-parser.yy @example -%define api.tokens.prefix "TOK_" +%define api.token.prefix "TOK_" %token END 0 "end of file" ASSIGN ":=" @@ -10804,11 +11072,11 @@ class defines a @dfn{position}, a single point in a file; Bison itself defines a class representing a @dfn{location}, a range composed of a pair of positions (possibly spanning several files). The location class is an inner class of the parser; the name is @code{Location} by default, and may also be -renamed using @samp{%define location_type "@var{class-name}"}. +renamed using @code{%define api.location.type "@var{class-name}"}. The location class treats the position as a completely opaque value. By default, the class name is @code{Position}, but this can be changed -with @samp{%define position_type "@var{class-name}"}. This class must +with @code{%define api.position.type "@var{class-name}"}. This class must be supplied by the user. @@ -10970,7 +11238,7 @@ In both cases, the scanner has to implement the following methods. @deftypemethod {Lexer} {void} yyerror (Location @var{loc}, String @var{msg}) This method is defined by the user to emit an error message. The first parameter is omitted if location tracking is not active. Its type can be -changed using @samp{%define location_type "@var{class-name}".} +changed using @code{%define api.location.type "@var{class-name}".} @end deftypemethod @deftypemethod {Lexer} {int} yylex () @@ -10988,7 +11256,7 @@ Return respectively the first position of the last token that @code{yylex} returned, and the first position beyond it. These methods are not needed unless location tracking is active. -The return type can be changed using @samp{%define position_type +The return type can be changed using @code{%define api.position.type "@var{class-name}".} @end deftypemethod @@ -11250,10 +11518,11 @@ comma-separated list. Default is @code{java.io.IOException}. @xref{Java Scanner Interface}. @end deffn -@deffn {Directive} {%define location_type} "@var{class}" +@deffn {Directive} {%define api.location.type} "@var{class}" The name of the class used for locations (a range between two positions). This class is generated as an inner class of the parser class by @command{bison}. Default is @code{Location}. +Formerly named @code{location_type}. @xref{Java Location Values}. @end deffn @@ -11268,9 +11537,10 @@ The name of the parser class. Default is @code{YYParser} or @xref{Java Bison Interface}. @end deffn -@deffn {Directive} {%define position_type} "@var{class}" +@deffn {Directive} {%define api.position.type} "@var{class}" The name of the class used for positions. This class must be supplied by the user. Default is @code{Position}. +Formerly named @code{position_type}. @xref{Java Location Values}. @end deffn @@ -12569,7 +12839,11 @@ London, Department of Computer Science, TR-00-12 (December 2000). @c LocalWords: getLVal defvar deftypefn deftypefnx gotos msgfmt Corbett LALR's @c LocalWords: subdirectory Solaris nonassociativity perror schemas Malloy ints @c LocalWords: Scannerless ispell american ChangeLog smallexample CSTYPE CLTYPE -@c LocalWords: clval CDEBUG cdebug deftypeopx yyterminate +@c LocalWords: clval CDEBUG cdebug deftypeopx yyterminate LocationType +@c LocalWords: parsers parser's +@c LocalWords: associativity subclasses precedences unresolvable runnable +@c LocalWords: allocators subunit initializations unreferenced untyped +@c LocalWords: errorVerbose subtype subtypes @c Local Variables: @c ispell-dictionary: "american"