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lib: parser: use reentrant mode on flex & bison

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This removes remaining global variables from the lexer, pushing the
lexer state into struct parser_ctx too.  At the same time, "cmd_yy" is
used as prefix for all parser & lexer routines.

The result is that (a) there is no collision anymore if a program uses
flex/bison and links libzebra, and (b) the parser is fully encapsulated
and could be called in parallel from multiple threads.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2016-11-16 15:03:51 +09:00
parent b07a15f82d
commit e9484f70b2
2 changed files with 50 additions and 38 deletions
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38
lib/command_lex.l
View File

@ -24,10 +24,7 @@
%{
#include "command_parse.h"
extern void set_lexer_string (const char *);
extern void cleanup_lexer (void);
YY_BUFFER_STATE buffer;
#define YYSTYPE CMD_YYSTYPE
%}
WORD (\-|\+)?[a-z\*][-+_a-zA-Z0-9\*]*
@ -45,27 +42,34 @@ RANGE \({NUMBER}[ ]?\-[ ]?{NUMBER}\)
%option nounput
%option noinput
%option outfile="command_lex.c"
%option header-file="command_lex.h"
%option prefix="cmd_yy"
%option reentrant
%option bison-bridge
%%
[ /t] /* ignore whitespace */;
{WORD} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return WORD;}
{IPV4} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return IPV4;}
{IPV4_PREFIX} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return IPV4_PREFIX;}
{IPV6} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return IPV6;}
{IPV6_PREFIX} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return IPV6_PREFIX;}
{VARIABLE} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return VARIABLE;}
{RANGE} {yylval.string = XSTRDUP(MTYPE_TMP, yytext); return RANGE;}
{WORD} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return WORD;}
{IPV4} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return IPV4;}
{IPV4_PREFIX} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return IPV4_PREFIX;}
{IPV6} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return IPV6;}
{IPV6_PREFIX} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return IPV6_PREFIX;}
{VARIABLE} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return VARIABLE;}
{RANGE} {yylval->string = XSTRDUP(MTYPE_TMP, yytext); return RANGE;}
. {return yytext[0];}
%%
void
set_lexer_string (const char *string)
YY_BUFFER_STATE buffer;
void set_lexer_string (yyscan_t *scn, const char *string)
{
buffer = yy_scan_string (string);
*scn = NULL;
yylex_init(scn);
buffer = yy_scan_string (string, *scn);
}
void
cleanup_lexer ()
void cleanup_lexer (yyscan_t *scn)
{
yy_delete_buffer (buffer);
// yy_delete_buffer (buffer, *scn);
yylex_destroy(*scn);
}

50
lib/command_parse.y
View File

@ -23,10 +23,18 @@
*/
%{
typedef union CMD_YYSTYPE CMD_YYSTYPE;
#define YYSTYPE CMD_YYSTYPE
#include "command_lex.h"
// compile with debugging facilities
#define YYDEBUG 1
%}
%define api.pure full
%define api.prefix {cmd_yy}
/* names for generated header and parser files */
%defines "command_parse.h"
%output "command_parse.c"
@ -39,16 +47,9 @@
#include "log.h"
#include "graph.h"
extern int
yylex (void);
extern void
set_lexer_string (const char *);
extern void
cleanup_lexer (void);
struct parser_ctx {
yyscan_t scanner;
struct cmd_element *el;
struct graph *graph;
@ -61,7 +62,6 @@
/* functionality this unit exports */
%code provides {
/* maximum length of a number, lexer will not match anything longer */
#define DECIMAL_STRLEN_MAX 20
}
@ -99,9 +99,13 @@
%type <subgraph> compound_token
%code {
extern void set_lexer_string (yyscan_t *scn, const char *string);
extern void cleanup_lexer (yyscan_t *scn);
/* bison declarations */
void
yyerror (struct parser_ctx *ctx, char const *msg);
cmd_yyerror (struct parser_ctx *ctx, char const *msg);
/* subgraph semantic value */
struct subgraph {
@ -133,10 +137,13 @@
static void
cleanup (struct parser_ctx *ctx);
#define scanner ctx->scanner
}
/* yyparse parameters */
%parse-param { struct parser_ctx *ctx }
%lex-param {yyscan_t scanner}
%parse-param {struct parser_ctx *ctx}
/* called automatically before yyparse */
%initial-action {
@ -145,9 +152,6 @@
ctx->startnode = vector_slot (ctx->graph->nodes, 0);
/* set string to parse */
set_lexer_string (ctx->el->string);
/* copy docstring and keep a pointer to the copy */
if (ctx->el->doc)
{
@ -272,7 +276,7 @@ placeholder_token:
token->max = strtoll (yylval.string, &yylval.string, 10);
// validate range
if (token->min > token->max) yyerror (ctx, "Invalid range.");
if (token->min > token->max) cmd_yyerror (ctx, "Invalid range.");
free ($1);
}
@ -399,6 +403,8 @@ option_token:
%%
#undef scanner
void
command_parse_format (struct graph *graph, struct cmd_element *cmd)
{
@ -407,8 +413,13 @@ command_parse_format (struct graph *graph, struct cmd_element *cmd)
// set to 1 to enable parser traces
yydebug = 0;
set_lexer_string (&ctx.scanner, cmd->string);
// parse command into DFA
yyparse (&ctx);
cmd_yyparse (&ctx);
/* cleanup lexer */
cleanup_lexer (&ctx.scanner);
// cleanup
cleanup (&ctx);
@ -430,9 +441,6 @@ cleanup (struct parser_ctx *ctx)
/* free resources */
free (ctx->docstr_start);
/* cleanup lexer */
cleanup_lexer ();
/* clear state pointers */
ctx->currnode = NULL;
ctx->docstr_start = ctx->docstr = NULL;
@ -453,7 +461,7 @@ terminate_graph (struct parser_ctx *ctx, struct graph_node *finalnode)
graph_new_node (ctx->graph, element, (void (*)(void *)) &del_cmd_element);
if (node_adjacent (finalnode, end_token_node))
yyerror (ctx, "Duplicate command.");
cmd_yyerror (ctx, "Duplicate command.");
graph_add_edge (finalnode, end_token_node);
graph_add_edge (end_token_node, end_element_node);