From caf00006f33a7cd6a35cd051add147bad4f33d8a Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Wed, 16 Sep 2015 23:43:30 +0200
Subject: [PATCH] add iterative API to LALR backend
---
src/backends/lalr.c | 5 +++-
src/backends/lr.c | 61 ++++++++++++++++++++++++++++++++++++++++++---
src/backends/lr.h | 3 +++
src/t_parser.c | 3 +++
4 files changed, 67 insertions(+), 5 deletions(-)
diff --git a/src/backends/lalr.c b/src/backends/lalr.c
index ec7a5b5f..975735a1 100644
--- a/src/backends/lalr.c
+++ b/src/backends/lalr.c
@@ -346,7 +346,10 @@ void h_lalr_free(HParser *parser)
HParserBackendVTable h__lalr_backend_vtable = {
.compile = h_lalr_compile,
.parse = h_lr_parse,
- .free = h_lalr_free
+ .free = h_lalr_free,
+ .parse_start = h_lr_parse_start,
+ .parse_chunk = h_lr_parse_chunk,
+ .parse_finish = h_lr_parse_finish
};
diff --git a/src/backends/lr.c b/src/backends/lr.c
index 161bbf96..3f99eb51 100644
--- a/src/backends/lr.c
+++ b/src/backends/lr.c
@@ -199,15 +199,14 @@ bool h_lrtable_row_empty(const HLRTable *table, size_t i)
/* LR driver */
-HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table,
- const HInputStream *stream)
+static
+HLREngine *h_lrengine_new_(HArena *arena, HArena *tarena, const HLRTable *table)
{
HLREngine *engine = h_arena_malloc(tarena, sizeof(HLREngine));
engine->table = table;
engine->state = 0;
engine->stack = h_slist_new(tarena);
- engine->input = *stream;
engine->merged[0] = NULL;
engine->merged[1] = NULL;
engine->arena = arena;
@@ -216,6 +215,14 @@ HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table,
return engine;
}
+HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table,
+ const HInputStream *stream)
+{
+ HLREngine *engine = h_lrengine_new_(arena, tarena, table);
+ engine->input = *stream;
+ return engine;
+}
+
static const HLRAction *
terminal_lookup(const HLREngine *engine, const HInputStream *stream)
{
@@ -352,7 +359,7 @@ HParseResult *h_lrengine_result(HLREngine *engine)
assert(!h_slist_empty(engine->stack));
HParsedToken *tok = engine->stack->head->elem;
HParseResult *res = make_result(engine->arena, tok);
- res->bit_length = engine->input.index * 8;
+ res->bit_length = (engine->input.pos + engine->input.index) * 8;
return res;
} else {
return NULL;
@@ -379,7 +386,53 @@ HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream*
return result;
}
+void h_lr_parse_start(HSuspendedParser *s)
+{
+ HLRTable *table = s->parser->backend_data;
+ assert(table != NULL);
+
+ HArena *arena = h_new_arena(s->mm__, 0); // will hold the results
+ HArena *tarena = h_new_arena(s->mm__, 0); // tmp, deleted after parse
+ HLREngine *engine = h_lrengine_new_(arena, tarena, table);
+ s->backend_state = engine;
+}
+
+bool h_lr_parse_chunk(HSuspendedParser* s, HInputStream *stream)
+{
+ HLREngine *engine = s->backend_state;
+ engine->input = *stream;
+
+ bool run = true;
+ while(run) {
+ // check input against table to determine which action to take
+ const HLRAction *action = h_lrengine_action(engine);
+ if(action == NEED_INPUT) {
+ // XXX assume lookahead 1
+ assert(engine->input.length - engine->input.index == 0);
+ break;
+ }
+
+ // execute action
+ run = h_lrengine_step(engine, action);
+ if(engine->input.overrun && !engine->input.last_chunk)
+ break;
+ }
+
+ *stream = engine->input;
+ return !run; // done if engine no longer running
+}
+
+HParseResult *h_lr_parse_finish(HSuspendedParser *s)
+{
+ HLREngine *engine = s->backend_state;
+
+ HParseResult *result = h_lrengine_result(engine);
+ if(!result)
+ h_delete_arena(engine->arena);
+ h_delete_arena(engine->tarena);
+ return result;
+}
/* Pretty-printers */
diff --git a/src/backends/lr.h b/src/backends/lr.h
index f9cb9a20..724d126c 100644
--- a/src/backends/lr.h
+++ b/src/backends/lr.h
@@ -134,6 +134,9 @@ const HLRAction *h_lrengine_action(const HLREngine *engine);
bool h_lrengine_step(HLREngine *engine, const HLRAction *action);
HParseResult *h_lrengine_result(HLREngine *engine);
HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream);
+void h_lr_parse_start(HSuspendedParser *s);
+bool h_lr_parse_chunk(HSuspendedParser* s, HInputStream *stream);
+HParseResult *h_lr_parse_finish(HSuspendedParser *s);
HParseResult *h_glr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream);
void h_pprint_lritem(FILE *f, const HCFGrammar *g, const HLRItem *item);
diff --git a/src/t_parser.c b/src/t_parser.c
index a8bdb0d0..3d54ff6b 100644
--- a/src/t_parser.c
+++ b/src/t_parser.c
@@ -883,6 +883,9 @@ void register_parser_tests(void) {
g_test_add_data_func("/core/parser/lalr/leftrec-ne", GINT_TO_POINTER(PB_LALR), test_leftrec_ne);
g_test_add_data_func("/core/parser/lalr/rightrec", GINT_TO_POINTER(PB_LALR), test_rightrec);
g_test_add_data_func("/core/parser/lalr/result_length", GINT_TO_POINTER(PB_LALR), test_result_length);
+ g_test_add_data_func("/core/parser/lalr/iterative", GINT_TO_POINTER(PB_LALR), test_iterative);
+ g_test_add_data_func("/core/parser/lalr/iterative/lookahead", GINT_TO_POINTER(PB_LALR), test_iterative_lookahead);
+ g_test_add_data_func("/core/parser/lalr/iterative/result_length", GINT_TO_POINTER(PB_LALR), test_iterative_result_length);
g_test_add_data_func("/core/parser/glr/token", GINT_TO_POINTER(PB_GLR), test_token);
g_test_add_data_func("/core/parser/glr/ch", GINT_TO_POINTER(PB_GLR), test_ch);
--
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