From 54ba62bfb7e77db43df7f50dbdfc9640bc10ebb2 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Wed, 19 Jun 2013 17:01:13 +0200
Subject: [PATCH] record conflicts in a special HLRAction type
---
src/backends/lalr.c | 13 ++++++++++---
src/backends/lr.c | 21 +++++++++++++++++++++
src/backends/lr.h | 13 ++++++++++---
src/backends/lr0.c | 24 +++++++++++++++---------
4 files changed, 56 insertions(+), 15 deletions(-)
diff --git a/src/backends/lalr.c b/src/backends/lalr.c
index fa67e5a7..698b106d 100644
--- a/src/backends/lalr.c
+++ b/src/backends/lalr.c
@@ -138,7 +138,8 @@ int h_lrtable_put(HLRTable *tbl, size_t state, HCFChoice *x, HLRAction *action)
HLRAction *prev = h_hashtable_get(tbl->rows[state], x);
if(prev && prev != action) {
// conflict
- h_slist_push(tbl->inadeq, (void *)(uintptr_t)state);
+ action = h_lr_conflict(tbl->arena, prev, action);
+ h_hashtable_put(tbl->rows[state], x, action);
return -1;
} else {
h_hashtable_put(tbl->rows[state], x, action);
@@ -221,6 +222,7 @@ int h_lalr_compile(HAllocator* mm__, HParser* parser, const void* params)
for(HSlistNode *x=inadeq->head; x; x=x->next) {
size_t state = (uintptr_t)x->elem;
+ bool inadeq = false;
// clear old forall entry, it's being replaced by more fine-grained ones
table->forall[state] = NULL;
@@ -255,7 +257,8 @@ int h_lalr_compile(HAllocator* mm__, HParser* parser, const void* params)
if(fs->end_branch) {
HCFChoice *terminal = h_arena_malloc(arena, sizeof(HCFChoice));
terminal->type = HCF_END;
- h_lrtable_put(table, state, terminal, action);
+ if(h_lrtable_put(table, state, terminal, action) < 0)
+ inadeq = true;
}
H_FOREACH(fs->char_branches, void *key, HStringMap *m)
if(!m->epsilon_branch)
@@ -265,10 +268,14 @@ int h_lalr_compile(HAllocator* mm__, HParser* parser, const void* params)
terminal->type = HCF_CHAR;
terminal->chr = key_char((HCharKey)key);
- h_lrtable_put(table, state, terminal, action);
+ if(h_lrtable_put(table, state, terminal, action) < 0)
+ inadeq = true;
H_END_FOREACH // lookahead character
} H_END_FOREACH // enhanced production
H_END_FOREACH // reducible item
+
+ if(inadeq)
+ h_slist_push(table->inadeq, (void *)(uintptr_t)state);
}
}
diff --git a/src/backends/lr.c b/src/backends/lr.c
index 2d329b13..bf066455 100644
--- a/src/backends/lr.c
+++ b/src/backends/lr.c
@@ -159,6 +159,25 @@ HLRAction *h_reduce_action(HArena *arena, const HLRItem *item)
return action;
}
+// adds 'new' to the branches of 'action'
+// returns a 'action' if it is already of type HLR_CONFLICT
+// allocates a new HLRAction otherwise
+HLRAction *h_lr_conflict(HArena *arena, HLRAction *action, HLRAction *new)
+{
+ if(action->type != HLR_CONFLICT) {
+ HLRAction *old = action;
+ action = h_arena_malloc(arena, sizeof(HLRAction));
+ action->type = HLR_CONFLICT;
+ action->branches = h_slist_new(arena);
+ h_slist_push(action->branches, old);
+ }
+
+ assert(action->type == HLR_CONFLICT);
+ h_slist_push(action->branches, new);
+
+ return action;
+}
+
/* LR driver */
@@ -239,6 +258,8 @@ bool h_lrengine_step(HLREngine *engine, const HLRAction *action)
if(action == NULL)
return false; // no handle recognizable in input, terminate
+ assert(action->type == HLR_SHIFT || action->type == HLR_REDUCE);
+
if(action->type == HLR_SHIFT) {
h_slist_push(left, (void *)(uintptr_t)engine->state);
h_slist_pop(right); // symbol (discard)
diff --git a/src/backends/lr.h b/src/backends/lr.h
index b95c1332..13e10d41 100644
--- a/src/backends/lr.h
+++ b/src/backends/lr.h
@@ -28,16 +28,22 @@ typedef struct HLRItem_ {
} HLRItem;
typedef struct HLRAction_ {
- enum {HLR_SHIFT, HLR_REDUCE} type;
+ enum {HLR_SHIFT, HLR_REDUCE, HLR_CONFLICT} type;
union {
- size_t nextstate; // used with SHIFT
+ // used with HLR_SHIFT
+ size_t nextstate;
+
+ // used with HLR_REDUCE
struct {
HCFChoice *lhs; // symbol carrying semantic actions etc.
size_t length; // # of symbols in rhs
#ifndef NDEBUG
HCFChoice **rhs; // NB: the rhs symbols are not needed for the parse
#endif
- } production; // used with REDUCE
+ } production;
+
+ // used with HLR_CONFLICT
+ HSlist *branches; // list of possible HLRActions
};
} HLRAction;
@@ -104,6 +110,7 @@ void h_lrtable_free(HLRTable *table);
HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table);
HLRAction *h_reduce_action(HArena *arena, const HLRItem *item);
HLRAction *h_shift_action(HArena *arena, size_t nextstate);
+HLRAction *h_lr_conflict(HArena *arena, HLRAction *action, HLRAction *new);
bool h_eq_symbol(const void *p, const void *q);
bool h_eq_lr_itemset(const void *p, const void *q);
diff --git a/src/backends/lr0.c b/src/backends/lr0.c
index aab2ad19..67cf2aa0 100644
--- a/src/backends/lr0.c
+++ b/src/backends/lr0.c
@@ -182,23 +182,29 @@ HLRTable *h_lr0_table(HCFGrammar *g, const HLRDFA *dfa)
// add reduce entries, record inadequate states
for(size_t i=0; i<dfa->nstates; i++) {
+ bool inadeq = false;
+
// find reducible items in state
H_FOREACH_KEY(dfa->states[i], HLRItem *item)
if(item->mark == item->len) { // mark at the end
- // check for conflicts
- // XXX store more informative stuff in the inadeq records?
+ HLRAction *reduce = h_reduce_action(arena, item);
+
+ // check for reduce/reduce conflict on forall
if(table->forall[i]) {
- // reduce/reduce conflict with a previous item
- h_slist_push(table->inadeq, (void *)(uintptr_t)i);
- } else if(!h_hashtable_empty(table->rows[i])) {
- // shift/reduce conflict with one of the row's entries
- h_slist_push(table->inadeq, (void *)(uintptr_t)i);
+ reduce = h_lr_conflict(arena, table->forall[i], reduce);
+ inadeq = true;
}
+ table->forall[i] = reduce;
- // set reduce action for the entire row
- table->forall[i] = h_reduce_action(arena, item);
+ // check for shift/reduce conflict with other entries
+ // NOTE: these are not recorded as HLR_CONFLICTs at this point
+ if(!h_hashtable_empty(table->rows[i]))
+ inadeq = true;
}
H_END_FOREACH
+
+ if(inadeq)
+ h_slist_push(table->inadeq, (void *)(uintptr_t)i);
}
return table;
--
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