152 lines
3.4 KiB
C
152 lines
3.4 KiB
C
//
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// Created by Mikael Vejdemo Johansson on 4/7/15.
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//
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// Intention: read in a parser, generate the system of equations for its
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// generating functions
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//
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#include <inttypes.h>
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#include "../src/backends/contextfree.h"
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#include "../src/backends/lr.h"
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#include <stdio.h>
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static const char *nonterminal_name(const HCFGrammar *g, const HCFChoice *nt)
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{
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static char buf[16] = {0}; // 14 characters in base 26 are enough for 64 bits
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// find nt's number in g
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size_t n = (uintptr_t)h_hashtable_get(g->nts, nt);
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// NB the start symbol (number 0) is always "A".
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int i;
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for(i=14; i>=0 && (n>0 || i==14); i--) {
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buf[i] = 'A' + n%26;
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n = n/26; // shift one digit
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}
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return buf+i+1;
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}
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void readsequence(FILE *file, uint32_t *count, uint32_t *length,
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const HCFGrammar *g, const HCFSequence *seq) {
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// tally up numbers of choices, and lengths of emitted strings.
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// Immediately emit any nonterminals encountered.
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HCFChoice** x = seq->items;
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if (*x == NULL) {
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return;
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} else {
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fprintf(file, "1");
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HCharset cs;
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unsigned int i, cscount=0;
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for(; *x; x++) {
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switch((*x)->type) {
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case HCF_CHAR:
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(*length)++;
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break;
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case HCF_END:
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break;
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case HCF_CHARSET:
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cs = (*x)->charset;
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for(i=0; i<256; i++) {
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if (charset_isset(cs, i)) {
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cscount++;
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}
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}
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*count *= cscount;
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break;
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default: // HCF_CHOICE, non-terminal symbol
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fprintf(file, "*%s(t)", nonterminal_name(g, *x));
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break;
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}
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}
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}
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}
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// For each nt in g->nts
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// For each choice in nt->key->seq
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// For all elements in sequence
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// Accumulate counts
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// Accumulate string lengths
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// Emit count*t^length
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void h_pprint_gfeqns(FILE *file, const HCFGrammar *g) {
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if (g->nts->used < 1) {
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return;
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}
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// determine maximum string length of symbol names
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int len;
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size_t s;
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for(len=1, s=26; s < g->nts->used; len++, s*=26);
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// iterate over g->nts
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size_t i;
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HHashTableEntry *hte;
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for(i=0; i < g->nts->capacity; i++) {
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for(hte = &g->nts->contents[i]; hte; hte = hte->next) {
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if (hte->key == NULL) {
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continue;
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}
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const HCFChoice *nt = hte->key;
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fprintf(file, "%s(t) = ", nonterminal_name(g, nt));
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for(HCFSequence **seq = nt->seq; *seq; seq++) {
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if (seq != nt->seq) {
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fprintf(file, " + ");
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}
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uint32_t count=1, length=0;
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readsequence(file, &count, &length, g, *seq);
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if(count == 1) {
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if(length == 1) {
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fprintf(file, "*t");
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}
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if(length > 1) {
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fprintf(file, "*t^%d", length);
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}
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} else if(count > 1) {
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if(length == 0) {
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fprintf(file, "*%d", count);
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}
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if(length == 1) {
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fprintf(file, "*%d*t", count);
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}
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if (length > 1) {
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fprintf(file, "*%d*t^%d", count, length);
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}
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}
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}
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fprintf(file, "\n");
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}
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}
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}
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int main(int argc, char **argv)
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{
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HAllocator *mm__ = &system_allocator;
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HParser *n = h_ch('n');
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HParser *E = h_indirect();
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HParser *T = h_choice(h_sequence(h_ch('('), E, h_ch(')'), NULL), n, NULL);
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HParser *E_ = h_choice(h_sequence(E, h_ch('-'), T, NULL), T, NULL);
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h_bind_indirect(E, E_);
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HParser *p = E;
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HCFGrammar *g = h_cfgrammar_(mm__, h_desugar_augmented(mm__, p));
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if (g == NULL) {
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fprintf(stderr, "h_cfgrammar failed\n");
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return 1;
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}
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printf("\n==== Generating functions ====\n");
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h_pprint_gfeqns(stdout, g);
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printf("\n==== Grammar ====\n");
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h_pprint_grammar(stdout, g, 0);
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}
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