From 107d8c092b9b38417f48af1e66f3df72a5e2fc8b Mon Sep 17 00:00:00 2001
From: Mikael Vejdemo-Johansson <michiexile@gmail.com>
Date: Tue, 7 Apr 2015 22:13:18 +0200
Subject: [PATCH] Generating function skeleton code
---
examples/SConscript | 3 +-
examples/explore_singular.c | 244 ++++++++++++++++++++++++++++++++++++
2 files changed, 246 insertions(+), 1 deletion(-)
create mode 100644 examples/explore_singular.c
diff --git a/examples/SConscript b/examples/SConscript
index 0932bdac..07c6e515 100644
--- a/examples/SConscript
+++ b/examples/SConscript
@@ -7,4 +7,5 @@ dns = example.Program('dns', ['dns.c', 'rr.c', 'dns_common.c'])
base64 = example.Program('base64', 'base64.c')
base64_sem1 = example.Program('base64_sem1', 'base64_sem1.c')
base64_sem2 = example.Program('base64_sem2', 'base64_sem2.c')
-env.Alias("examples", [dns, base64, base64_sem1, base64_sem2])
\ No newline at end of file
+singular = example.Program('explore_singular', 'explore_singular.c')
+env.Alias("examples", [dns, base64, base64_sem1, base64_sem2, singular])
\ No newline at end of file
diff --git a/examples/explore_singular.c b/examples/explore_singular.c
new file mode 100644
index 00000000..3c751451
--- /dev/null
+++ b/examples/explore_singular.c
@@ -0,0 +1,244 @@
+//
+// Created by Mikael Vejdemo Johansson on 4/7/15.
+//
+// Intention: read in a parser, generate the system of equations for its
+// generating functions
+//
+
+#include <inttypes.h>
+#include "../src/backends/contextfree.h"
+#include "../src/backends/lr.h"
+#include <stdio.h>
+
+void h_pprint_gfexpr(FILE *file, const HCFGrammar *g, HCFSequence *seq) {
+ HCFChoice **x = seq->items;
+
+ if (*x == NULL) { // empty sequence
+ fprintf(file, "1\n");
+ } else {
+ while (*x) {
+ if (x != seq->items) {
+ fprintf(file, " + ");
+ }
+ // consume items
+ // if a string,
+ // count its length
+ // output t^length
+
+ if ((*x)->type == HCF_CHAR) {
+ uint32_t count = 0;
+ for(; *x; x++, count++) {
+ if ((*x)->type != HCF_CHAR) {
+ break;
+ }
+ }
+ fprintf(file, "t^%d", count);
+ } else {
+ uint32_t count=0, n, i=0;
+ switch((*x)->type) {
+ case HCF_CHAR:
+ // should not be possible
+ break;
+ case HCF_END:
+ // does not generate any output symbols: value 0
+ break;
+ case HCF_CHARSET:
+ for(i=0; i<256; i++) {
+ if (charset_isset((*x)->charset, i)) {
+ count++;
+ }
+ }
+ fprintf(file, "%d*t", count);
+ break;
+ default:
+ n = (uint8_t)(uintptr_t)h_hashtable_get(g->nts, x);
+
+ fprintf(file, "%c(t)", 'A'+n);
+ }
+ x++;
+ }
+ }
+ }
+}
+
+
+void h_pprint_gfeqns_NOTUSED(FILE *file, const HCFGrammar *g) {
+ if (g->nts->used < 1) {
+ return;
+ }
+
+ // determine maximum string length of symbol names
+ int len;
+ size_t s;
+ for(len=1, s=26; s < g->nts->used; len++, s*=26);
+
+ // iterate over g->nts
+ size_t i;
+ HHashTableEntry *hte;
+ for(i=0; i < g->nts->capacity; i++) {
+ for(hte = &g->nts->contents[i]; hte; hte = hte->next) {
+ if (hte->key == NULL) {
+ continue;
+ }
+ const HCFChoice *lhs = hte->key; // production's left-hand symbol
+ assert(lhs->type == HCF_CHOICE);
+
+ uint8_t n = (uint8_t)(uintptr_t)h_hashtable_get(g->nts, lhs);
+ fprintf(file, "%c(t) = ", 'A'+n);
+
+ HCFSequence **p = lhs->seq;
+ if (*p == NULL) {
+ return; // shouldn't happen
+ }
+
+ h_pprint_gfexpr(file, g, *p);
+ for(; *p; p++) {
+ fprintf(file, "\t");
+ h_pprint_gfexpr(file, g, *p);
+ fprintf(file, "\n");
+ }
+ }
+ }
+}
+
+
+static const char *nonterminal_name(const HCFGrammar *g, const HCFChoice *nt)
+{
+ static char buf[16] = {0}; // 14 characters in base 26 are enough for 64 bits
+
+ // find nt's number in g
+ size_t n = (uintptr_t)h_hashtable_get(g->nts, nt);
+
+ // NB the start symbol (number 0) is always "A".
+ int i;
+ for(i=14; i>=0 && (n>0 || i==14); i--) {
+ buf[i] = 'A' + n%26;
+ n = n/26; // shift one digit
+ }
+
+ return buf+i+1;
+}
+
+
+
+void readsequence(FILE *file, uint32_t *count, uint32_t *length,
+ const HCFGrammar *g, const HCFSequence *seq) {
+ // tally up numbers of choices, and lengths of emitted strings.
+ // Immediately emit any nonterminals encountered.
+ HCFChoice** x = seq->items;
+
+ if (*x == NULL) {
+ return;
+ } else {
+ fprintf(file, "1");
+ HCharset cs;
+ unsigned int i, cscount=0;
+ for(; *x; x++) {
+ switch((*x)->type) {
+ case HCF_CHAR:
+ (*length)++;
+ break;
+ case HCF_END:
+ break;
+ case HCF_CHARSET:
+ cs = (*x)->charset;
+ for(i=0; i<256; i++) {
+ if (charset_isset(cs, i)) {
+ cscount++;
+ }
+ }
+ *count *= cscount;
+ break;
+ default: // HCF_CHOICE, non-terminal symbol
+ fprintf(file, "*%s(t)", nonterminal_name(g, *x));
+ break;
+ }
+ }
+ }
+}
+
+// For each nt in g->nts
+// For each choice in nt->key->seq
+// For all elements in sequence
+// Accumulate counts
+// Accumulate string lengths
+// Emit count*t^length
+void h_pprint_gfeqns(FILE *file, const HCFGrammar *g) {
+ if (g->nts->used < 1) {
+ return;
+ }
+
+ // determine maximum string length of symbol names
+ int len;
+ size_t s;
+ for(len=1, s=26; s < g->nts->used; len++, s*=26);
+
+ // iterate over g->nts
+ size_t i;
+ HHashTableEntry *hte;
+ for(i=0; i < g->nts->capacity; i++) {
+ for(hte = &g->nts->contents[i]; hte; hte = hte->next) {
+ if (hte->key == NULL) {
+ continue;
+ }
+
+ const HCFChoice *nt = hte->key;
+ fprintf(file, "%s(t) = ", nonterminal_name(g, nt));
+
+
+ for(HCFSequence **seq = nt->seq; *seq; seq++) {
+ if (seq != nt->seq) {
+ fprintf(file, " + ");
+ }
+ uint32_t count=1, length=0;
+ readsequence(file, &count, &length, g, *seq);
+ if(count == 1) {
+ if(length == 1) {
+ fprintf(file, "*t");
+ }
+ if(length > 1) {
+ fprintf(file, "*t^%d", length);
+ }
+ } else if(count > 1) {
+ if(length == 0) {
+ fprintf(file, "*%d", count);
+ }
+ if(length == 1) {
+ fprintf(file, "*%d*t", count);
+ }
+ if (length > 1) {
+ fprintf(file, "*%d*t^%d", count, length);
+ }
+ }
+ }
+
+ fprintf(file, "\n");
+ }
+ }
+}
+
+
+
+
+int main(int argc, char **argv)
+{
+ HAllocator *mm__ = &system_allocator;
+
+ HParser *n = h_ch('n');
+ HParser *E = h_indirect();
+ HParser *T = h_choice(h_sequence(h_ch('('), E, h_ch(')'), NULL), n, NULL);
+ HParser *E_ = h_choice(h_sequence(E, h_ch('-'), T, NULL), T, NULL);
+ h_bind_indirect(E, E_);
+ HParser *p = E;
+
+ HCFGrammar *g = h_cfgrammar_(mm__, h_desugar_augmented(mm__, p));
+ if (g == NULL) {
+ fprintf(stderr, "h_cfgrammar failed\n");
+ return 1;
+ }
+ printf("\n==== Generating functions ====\n");
+ h_pprint_gfeqns(stdout, g);
+
+ printf("\n==== Grammar ====\n");
+ h_pprint_grammar(stdout, g, 0);
+}
--
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