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* src/gram.h (rule_s): Member assoc' is of type associativity'.

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Akim Demaille
2001-12-29 14:26:21 +00:00
parent 931394cbc1
commit aea13e9790
2 changed files with 38 additions and 23 deletions
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5
ChangeLog
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@@ -1,3 +1,8 @@
2001-12-29 Akim Demaille <akim@epita.fr>
* src/gram.h (rule_s): Member `assoc' is of type `associativity'.
2001-12-29 Akim Demaille <akim@epita.fr> 2001-12-29 Akim Demaille <akim@epita.fr>
* tests/actions.at (Mid-rule actions): Output on a single line * tests/actions.at (Mid-rule actions): Output on a single line

56
src/gram.h
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@@ -21,39 +21,49 @@
#ifndef GRAM_H_ #ifndef GRAM_H_
# define GRAM_H_ # define GRAM_H_
/* representation of the grammar rules: /* Representation of the grammar rules:
ntokens is the number of tokens, and nvars is the number of NTOKENS is the number of tokens, and NVARS is the number of
variables (nonterminals). nsyms is the total number, ntokens + variables (nonterminals). NSYMS is the total number, ntokens +
nvars. nvars.
(the true number of token values assigned is ntokens reduced by one
for each alias declaration)
Each symbol (either token or variable) receives a symbol number. Each symbol (either token or variable) receives a symbol number.
Numbers 0 to ntokens-1 are for tokens, and ntokens to nsyms-1 are Numbers 0 to NTOKENS - 1 are for tokens, and NTOKENS to NSYMS - 1
for variables. Symbol number zero is the end-of-input token. This are for variables. Symbol number zero is the end-of-input token.
token is counted in ntokens. This token is counted in ntokens. The true number of token values
assigned is NTOKENS reduced by one for each alias declaration.
The rules receive rule numbers 1 to nrules in the order they are The rules receive rule numbers 1 to NRULES in the order they are
written. Actions and guards are accessed via the rule number. written. More precisely Bison augments the grammar with the
initial rule, `$axiom: START-SYMBOL EOF', which is numbered 1, all
the user rules are 2, 3 etc. Each time a rule number is presented
to the user, we subtract 1, so *displayed* rule numbers are 0, 1,
2...
Internally, we cannot use the number 0 for a rule because for
instance RITEM stores both symbol (the RHS) and rule numbers: the
symbols are shorts >= 0, and rule number are stored negative.
Therefore 0 cannot be used, since it would be both the rule number
0, and the token EOF).
Actions and guards are accessed via the rule number.
The rules themselves are described by several arrays: amongst which The rules themselves are described by several arrays: amongst which
RITEM, and RULES. RITEM, and RULES.
RULES is an array of struct rule_s, which members are: RULES is an array of struct rule_s, which members are:
RULES[R].lhs -- the symbol number of the left hand side of RULES[R].lhs -- the symbol number of the left hand side of rule R.
rule R. If -1, the rule has been thrown out by reduce.c and should If -1, the rule has been thrown out by reduce.c and should be
be ignored. ignored.
RULES[R].rhs -- the index in RITEM of the beginning of the RULES[R].rhs -- the index in RITEM of the beginning of the portion
portion for rule R. for rule R.
RULES[R].prec -- the precedence level of R. RULES[R].prec -- the precedence level of R.
RULES[R].precsym -- the symbol-number of the symbol in %prec RULES[R].precsym -- the symbol-number of the symbol in %prec for R
for R (if any). (if any).
RULES[R].assoc -- the associativity of R. RULES[R].assoc -- the associativity of R.
@@ -72,20 +82,20 @@
The portions of RITEM come in order of increasing rule number and The portions of RITEM come in order of increasing rule number and
are followed by an element which is zero to mark the end. nitems are followed by an element which is zero to mark the end. nitems
is the total length of ritem, not counting the final zero. Each is the total length of ritem, not counting the final zero. Each
element of ritem is called an "item" and its index in ritem is an element of RITEM is called an "item" and its index in RITEM is an
item number. item number.
Item numbers are used in the finite state machine to represent Item numbers are used in the finite state machine to represent
places that parsing can get to. places that parsing can get to.
SYMBOLS[I]->PREC records the precedence level of each symbol. SYMBOLS[I]->prec records the precedence level of each symbol.
Precedence levels are assigned in increasing order starting with 1 Precedence levels are assigned in increasing order starting with 1
so that numerically higher precedence values mean tighter binding so that numerically higher precedence values mean tighter binding
as they ought to. Zero as a symbol or rule's precedence means none as they ought to. Zero as a symbol or rule's precedence means none
is assigned. is assigned.
Associativities are recorded similarly in rassoc and sassoc. */ Associativities are recorded similarly in SYMBOLS[I]->assoc. */
#define ISTOKEN(s) ((s) < ntokens) #define ISTOKEN(s) ((s) < ntokens)
@@ -102,7 +112,7 @@ extern int nritems;
extern int start_symbol; extern int start_symbol;
/* associativity values in elements of rassoc, sassoc. */ /* Associativity values for tokens and rules. */
typedef enum typedef enum
{ {
right_assoc, right_assoc,
@@ -117,7 +127,7 @@ typedef struct rule_s
short rhs; short rhs;
short prec; short prec;
short precsym; short precsym;
short assoc; associativity assoc;
short line; short line;
bool useful; bool useful;