-Ceci est le fichier Info bison.info, produit par Makeinfo version 4.0 à
-partir bison.texinfo.
+Ceci est le fichier Info bison.info, produit par Makeinfo version 4.0b
+à partir bison.texinfo.
START-INFO-DIR-ENTRY
* bison: (bison). GNU Project parser generator (yacc replacement).
\1f
File: bison.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
- This manual documents version 1.28a of Bison.
+ This manual documents version 1.28c of Bison.
* Menu:
it Yacc-compatible. Wilfred Hansen of Carnegie Mellon University added
multi-character string literals and other features.
- This edition corresponds to version 1.28a of Bison.
+ This edition corresponds to version 1.28c of Bison.
\1f
File: bison.info, Node: Conditions, Next: Copying, Prev: Introduction, Up: Top
**************************
Version 2, June 1991
-
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
modification follow.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-
0. This License applies to any program or other work which contains a
notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program",
a semantic value (the value of an integer,
the name of an identifier, etc.).
* Semantic Actions:: Each rule can have an action containing C code.
+* Locations Overview:: Tracking Locations.
* Bison Parser:: What are Bison's input and output,
how is the output used?
* Stages:: Stages in writing and running Bison grammars.
is a tree structure describing the meaning of the expression.
\1f
-File: bison.info, Node: Semantic Actions, Next: Bison Parser, Prev: Semantic Values, Up: Concepts
+File: bison.info, Node: Semantic Actions, Next: Locations Overview, Prev: Semantic Values, Up: Concepts
Semantic Actions
================
from the values of the two subexpressions.
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-File: bison.info, Node: Bison Parser, Next: Stages, Prev: Semantic Actions, Up: Concepts
+File: bison.info, Node: Locations Overview, Next: Bison Parser, Prev: Semantic Actions, Up: Concepts
+
+Locations
+=========
+
+ Many applications, like interpreters or compilers, have to produce
+verbose and useful error messages. To achieve this, one must be able to
+keep track of the "textual position", or "location", of each syntactic
+construct. Bison provides a mechanism for handling these locations.
+
+ Each token has a semantic value. In a similar fashion, each token
+has an associated location, but the type of locations is the same for
+all tokens and groupings. Moreover, the output parser is equipped with
+a default data structure for storing locations (*note Locations::, for
+more details).
+
+ Like semantic values, locations can be reached in actions using a
+dedicated set of constructs. In the example above, the location of the
+whole grouping is `@$', while the locations of the subexpressions are
+`@1' and `@3'.
+
+ When a rule is matched, a default action is used to compute the
+semantic value of its left hand side (*note Actions::). In the same
+way, another default action is used for locations. However, the action
+for locations is general enough for most cases, meaning there is
+usually no need to describe for each rule how `@$' should be formed.
+When building a new location for a given grouping, the default behavior
+of the output parser is to take the beginning of the first symbol, and
+the end of the last symbol.
+
+\1f
+File: bison.info, Node: Bison Parser, Next: Stages, Prev: Locations Overview, Up: Concepts
Bison Output: the Parser File
=============================
* Gen: Rpcalc Gen. Running Bison on the grammar file.
* Comp: Rpcalc Compile. Run the C compiler on the output code.
-\1f
-File: bison.info, Node: Rpcalc Decls, Next: Rpcalc Rules, Up: RPN Calc
-
-Declarations for `rpcalc'
--------------------------
-
- Here are the C and Bison declarations for the reverse polish notation
-calculator. As in C, comments are placed between `/*...*/'.
-
- /* Reverse polish notation calculator. */
-
- %{
- #define YYSTYPE double
- #include <math.h>
- %}
-
- %token NUM
-
- %% /* Grammar rules and actions follow */
-
- The C declarations section (*note The C Declarations Section: C
-Declarations.) contains two preprocessor directives.
-
- The `#define' directive defines the macro `YYSTYPE', thus specifying
-the C data type for semantic values of both tokens and groupings (*note
-Data Types of Semantic Values: Value Type.). The Bison parser will use
-whatever type `YYSTYPE' is defined as; if you don't define it, `int' is
-the default. Because we specify `double', each token and each
-expression has an associated value, which is a floating point number.
-
- The `#include' directive is used to declare the exponentiation
-function `pow'.
-
- The second section, Bison declarations, provides information to
-Bison about the token types (*note The Bison Declarations Section:
-Bison Declarations.). Each terminal symbol that is not a
-single-character literal must be declared here. (Single-character
-literals normally don't need to be declared.) In this example, all the
-arithmetic operators are designated by single-character literals, so the
-only terminal symbol that needs to be declared is `NUM', the token type
-for numeric constants.
-
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