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grammar.c
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grammar.c
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#include "cparse.h"
#include "grammar.h"
#include "util.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
Grammar *makeGrammar() {
Grammar *grammar = calloc(1, sizeof(Grammar));
grammar->rules = calloc(ARRAY_CAPACITY, sizeof(Rule *));
grammar->terminals = calloc(ARRAY_CAPACITY, sizeof(char *));
grammar->nonterminals = calloc(ARRAY_CAPACITY, sizeof(char *));
grammar->first = makeSet();
grammar->follow = makeSet();
return grammar;
}
Rule *makeRule() {
Rule *rule = calloc(1, sizeof(Rule));
rule->right = calloc(ARRAY_CAPACITY, sizeof(char *));
return rule;
}
void addRuleToArray(Rule **array, Rule *value) {
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (!array[i]) {
array[i] = value;
break;
}
}
}
void computeFirst(Grammar *grammar, char *nonterminal) {
for (int j = 0; j < ARRAY_CAPACITY; j++) {
if (grammar->rules[j] && strcmp(grammar->rules[j]->left, nonterminal) == 0) {
if (grammar->rules[j]->right[0]) {
if (strcmp(grammar->rules[j]->right[0], "epsilon") == 0) {
addToSet(grammar->first, nonterminal, "epsilon");
} else if (inArray(grammar->terminals, grammar->rules[j]->right[0])) {
addToSet(grammar->first, nonterminal, grammar->rules[j]->right[0]);
} else if (inArray(grammar->nonterminals, grammar->rules[j]->right[0])) {
int count = 0;
if (strcmp(grammar->rules[j]->left, grammar->rules[j]->right[count]) != 0)
computeFirst(grammar, grammar->rules[j]->right[count]);
if (!inSet(grammar->first, grammar->rules[j]->right[count], "epsilon")) {
addAllToSet(grammar->first, nonterminal, findValuesInSet(grammar->first, grammar->rules[j]->right[0]));
} else {
addAllToSet(grammar->first, nonterminal, findValuesInSet(grammar->first, grammar->rules[j]->right[0])); // TODO: Minus epsilon?
while (true) {
computeFirst(grammar, grammar->rules[j]->right[++count]);
addAllToSet(grammar->first, nonterminal, findValuesInSet(grammar->first, grammar->rules[j]->right[count]));
if (!inSet(grammar->first, grammar->rules[j]->right[count], "epsilon"))
break;
}
}
}
}
}
}
}
void computeFirstSet(Grammar *grammar) {
for (int i = 0; i < ARRAY_CAPACITY; i++)
if (grammar->nonterminals[i])
computeFirst(grammar, grammar->nonterminals[i]);
}
void computeFollowSet(Grammar *grammar) {
for (int i = 0; i < ARRAY_CAPACITY; i++)
if (grammar->nonterminals[i] && !isKeyInSet(grammar->follow, grammar->nonterminals[i]))
createSetItem(grammar->follow, grammar->nonterminals[i]);
while (true) {
bool hasChanged = false;
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->nonterminals[i]) {
char *nonterminal = grammar->nonterminals[i];
if (strcmp(nonterminal, "cparseStart") == 0) {
addToSet(grammar->follow, nonterminal, "$");
continue;
}
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->rules[i]) {
for (int j = 0; j < ARRAY_CAPACITY; j++) {
if (grammar->rules[i]->right[j] && strcmp(grammar->rules[i]->right[j], nonterminal) == 0) {
SetItem *first = NULL;
if (j == getValuesLength(grammar->rules[i]->right) - 1) {
first = findInSet(grammar->follow, grammar->rules[i]->left);
} else {
SetItem *rightFirst = findInSet(grammar->first, grammar->rules[i]->right[j + 1]);
if (rightFirst)
first = copySetItem(rightFirst); // TODO: Why copy?
else {
first = calloc(1, sizeof(SetItem));
first->values = calloc(ARRAY_CAPACITY, sizeof(SetItem));
first->values[0] = grammar->rules[i]->right[j + 1];
}
if (inSetItem(first, "epsilon")) {
removeFromSetItem(first, "epsilon");
addAllToSetItem(first, findValuesInSet(grammar->follow, grammar->rules[i]->left));
}
}
SetItem *follow = findInSet(grammar->follow, nonterminal);
if (!allInSetItem(follow, first->values)) {
hasChanged = true;
addAllToSetItem(follow, first->values);
}
}
}
}
}
}
}
if (!hasChanged) break;
}
}
Grammar *cparseGrammar(char *grammarString) {
Grammar *grammar = makeGrammar();
char *rest, *token, *grammarStringPtr = grammarString;
while ((token = strtok_r(grammarStringPtr, "\n", &rest))) {
char *left = trim(strtok(token, "->"));
if (!grammar->start) {
grammar->start = left;
Rule *rule = makeRule();
rule->left = "cparseStart";
addCharPtrToArray(rule->right, left);
addRuleToArray(grammar->rules, rule);
addCharPtrToArray(grammar->nonterminals, "cparseStart");
}
addCharPtrToArrayUnique(grammar->nonterminals, left);
char *right = strtok(NULL, "->");
char *singleRight = strtok(right, "|");
while (singleRight) {
singleRight = trim(singleRight);
char **singleRightWords = stringToWords(singleRight);
for (int i = 0; i < ARRAY_CAPACITY; i++)
if (singleRightWords[i] && strcmp(singleRightWords[i], "epsilon") != 0)
addCharPtrToArrayUnique(grammar->terminals, singleRightWords[i]);
Rule *rule = makeRule();
rule->left = left;
rule->right = singleRightWords;
addRuleToArray(grammar->rules, rule);
singleRight = strtok(NULL, "|");
}
grammarStringPtr = rest;
}
for (int i = 0; i < ARRAY_CAPACITY; i++)
if (grammar->nonterminals[i])
removeCharPtrFromArray(grammar->terminals, grammar->nonterminals[i]);
computeFirstSet(grammar);
computeFollowSet(grammar);
return grammar;
}
char *getGrammarAsString(Grammar *grammar) {
char *result = calloc(100000, sizeof(char));
sprintf(result, "Start nonterminal: ");
sprintf(result + strlen(result), grammar->start);
sprintf(result + strlen(result), "\nTerminals:");
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->terminals[i]) {
sprintf(result + strlen(result), " ");
sprintf(result + strlen(result), grammar->terminals[i]);
}
}
sprintf(result + strlen(result), "\nNon-terminals:");
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->nonterminals[i]) {
sprintf(result + strlen(result), " ");
sprintf(result + strlen(result), grammar->nonterminals[i]);
}
}
sprintf(result + strlen(result), "\nRules: ");
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->rules[i]) {
sprintf(result + strlen(result), grammar->rules[i]->left);
sprintf(result + strlen(result), " ->");
for (int j = 0; j < ARRAY_CAPACITY; j++) {
if (grammar->rules[i]->right[j]) {
sprintf(result + strlen(result), " ");
sprintf(result + strlen(result), grammar->rules[i]->right[j]);
}
}
sprintf(result + strlen(result), " && ");
}
}
result[strlen(result) - 4] = '\0';
sprintf(result + strlen(result), "\nFirst set:");
for (int i = 0; i < ARRAY_CAPACITY; i++) {
if (grammar->first[i]) {
sprintf(result + strlen(result), " ");
sprintf(result + strlen(result), grammar->first[i]->key);
sprintf(result + strlen(result), ": [");
for (int j = 0; j < ARRAY_CAPACITY; j++) {
if (grammar->first[i]->values[j]) {
sprintf(result + strlen(result), grammar->first[i]->values[j]);
sprintf(result + strlen(result), ", ");
}
}
result[strlen(result) - 2] = '\0';
sprintf(result + strlen(result), "]");
}
}
sprintf(result + strlen(result), "\nFollow set:");
for (int i = 0; i < ARRAY_CAPACITY; i++) {
bool empty = true;
if (grammar->follow[i]) {
sprintf(result + strlen(result), " ");
sprintf(result + strlen(result), grammar->follow[i]->key);
sprintf(result + strlen(result), ": [");
for (int j = 0; j < ARRAY_CAPACITY; j++) {
if (grammar->follow[i]->values[j]) {
empty = false;
sprintf(result + strlen(result), grammar->follow[i]->values[j]);
sprintf(result + strlen(result), ", ");
}
}
if (!empty) result[strlen(result) - 2] = '\0';
sprintf(result + strlen(result), "]");
}
}
return result;
}