From a72aff9b3924ba37f4cfee4ac2cebc913f8f30e8 Mon Sep 17 00:00:00 2001
From: Mikael Vejdemo-Johansson <michiexile@gmail.com>
Date: Wed, 8 Apr 2015 17:32:12 +0200
Subject: [PATCH] refactored out the grammar handling. handles epsilons better
---
examples/SConscript | 5 +-
examples/grammar.c | 148 ++++++++++++++++++++++++++++++++++++++++++++
examples/grammar.h | 46 ++++++++++++++
examples/ties.c | 141 +----------------------------------------
4 files changed, 197 insertions(+), 143 deletions(-)
create mode 100644 examples/grammar.c
create mode 100644 examples/grammar.h
diff --git a/examples/SConscript b/examples/SConscript
index 456545c2..06947216 100644
--- a/examples/SConscript
+++ b/examples/SConscript
@@ -7,6 +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')
-singular = example.Program('explore_singular', 'explore_singular.c')
-ties = example.Program('ties', 'ties.c')
-env.Alias("examples", [dns, base64, base64_sem1, base64_sem2, singular, ties])
\ No newline at end of file
+ties = example.Program('ties', ['ties.c', 'grammar.c'])
+env.Alias("examples", [dns, base64, base64_sem1, base64_sem2, ties])
\ No newline at end of file
diff --git a/examples/grammar.c b/examples/grammar.c
new file mode 100644
index 00000000..f722edf0
--- /dev/null
+++ b/examples/grammar.c
@@ -0,0 +1,148 @@
+// Generates a system of equations for generating functions from a grammar.
+//
+// (c) 2015 Mikael Vejdemo-Johansson <mikael@johanssons.org>
+//
+
+// If a desugared parser has user_data set, the generating function systems will try
+// to interpret it as a string:
+//
+// If this string for an h_ch starts with the character 0, then that character
+// will have weight 0 in the generating function.
+//
+// Use the remaining string to set the preferred name of that parser in the
+// generating function.
+//
+
+#include <inttypes.h>
+#include "../src/backends/contextfree.h"
+#include "../src/backends/lr.h"
+#include "grammar.h"
+#include <stdio.h>
+
+const char *nonterminal_name(const HCFGrammar *g, const HCFChoice *nt) {
+ if(nt->user_data != NULL) {
+ if(*(char*)(nt->user_data) != '0') {
+ // user_data is a non-empty string
+ return nt->user_data;
+ } else {
+ return nt->user_data+1;
+ }
+ }
+
+ 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;
+
+ fprintf(file, "1");
+ if (*x == NULL) {
+ // empty sequence
+ // GF is 1
+ return;
+ } else {
+ char has_user_data = (*x)->user_data != NULL && *(char*)(*x)->user_data != 0;
+ HCharset cs;
+ unsigned int i, cscount=0;
+ for(; *x; x++) {
+ switch((*x)->type) {
+ case HCF_CHAR:
+ if(!(has_user_data && *(char*)(*x)->user_data == '0')) {
+ (*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");
+ }
+ }
+}
diff --git a/examples/grammar.h b/examples/grammar.h
new file mode 100644
index 00000000..b42eced4
--- /dev/null
+++ b/examples/grammar.h
@@ -0,0 +1,46 @@
+// Generates a system of equations for generating functions from a grammar.
+//
+// (c) 2015 Mikael Vejdemo-Johansson <mikael@johanssons.org>
+//
+
+// Currently does absolutely no elegance, no caching of information, but rather
+// just prints the generating functions to a provided FILE*.
+//
+
+
+// If a desugared parser has user_data set, the generating function systems will try
+// to interpret it as a string:
+//
+// If this string for an h_ch starts with the character 0, then that character
+// will have weight 0 in the generating function.
+//
+// Use the remaining string to set the preferred name of that parser in the
+// generating function.
+//
+
+#ifndef HAMMER_GRAMMAR__H
+#define HAMMER_GRAMMAR__H
+
+#include "../src/backends/contextfree.h"
+#include "../src/backends/lr.h"
+
+
+// Filched from cfgrammar.c this function extracts the name from user_data if it
+// is set; otherwise assigns a name automatically from its position in some
+// ordering of non-terminals.
+const char *nonterminal_name(const HCFGrammar *g, const HCFChoice *nt);
+
+// This function prints out the monomial generated by a single HCFSequence
+// It returns the resulting exponent for t in length and the number of alternatives
+// accumulated in length. The monomial is (mostly) printed out to the provided FILE*,
+// the caller is responsible for adding a scalar and a power of t to the printout.
+void readsequence(FILE *file, uint32_t *count, uint32_t *length,
+ const HCFGrammar *g, const HCFSequence *seq);
+
+// This function walks through a grammar and generates an equation for each
+// production rule. The results are printed out to the provided FILE*.
+void h_pprint_gfeqns(FILE *file, const HCFGrammar *g);
+
+
+
+#endif
diff --git a/examples/ties.c b/examples/ties.c
index a379b5c7..09f6b707 100644
--- a/examples/ties.c
+++ b/examples/ties.c
@@ -1,6 +1,3 @@
-//
-// Created by Mikael Vejdemo Johansson on 4/7/15.
-//
// Intention: read in a parser, generate the system of equations for its
// generating functions
//
@@ -8,148 +5,12 @@
#include <inttypes.h>
#include "../src/backends/contextfree.h"
#include "../src/backends/lr.h"
+#include "grammar.h"
#include <stdio.h>
HAllocator *mm__;
-// If a parser has user_data set, the generating function systems will try
-// to interpret it as a string:
-//
-// If this string for an h_ch starts with the character 0, then that character
-// will have weight 0 in the generating function.
-//
-// Use the remaining string to set the preferred name of that parser in the
-// generating function.
-
-
-
-static const char *nonterminal_name(const HCFGrammar *g, const HCFChoice *nt) {
- if(nt->user_data != NULL) {
- if(*(char*)(nt->user_data) != '0') {
- // user_data is a non-empty string
- return nt->user_data;
- } else {
- return nt->user_data+1;
- }
- }
-
- 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 {
- char has_user_data = (*x)->user_data != NULL && *(char*)(*x)->user_data != 0;
- fprintf(file, "1");
- HCharset cs;
- unsigned int i, cscount=0;
- for(; *x; x++) {
- switch((*x)->type) {
- case HCF_CHAR:
- if(!(has_user_data && *(char*)(*x)->user_data == '0')) {
- (*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");
- }
- }
-}
-
HParser* cfExample() {
HParser *n = h_ch('n');
HParser *E = h_indirect();
--
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