Implement plus desugaring

lib/desugar.c

@@ -5,8 +5,70 @@
 
 #include "desugar.h"
 
+#include <assert.h>
 #include <stdlib.h>
+#include <string.h>
+
+static void deep_copy_term(parse_term_t *dst, parse_term_t *src);
+
+static void deep_copy_sequence(parse_sequence_t *dst, parse_sequence_t *src)
+{
+	dst->count = dst->capacity = src->count;
+	dst->contents = malloc(dst->capacity * sizeof(parse_term_t));
+	for (int i = 0; i < dst->count; ++i)
+		deep_copy_term(&dst->contents[i], &src->contents[i]);
+}
+
+static void deep_copy_term(parse_term_t *dst, parse_term_t *src)
+{
+	assert(PARSE_TERM_WILDCARD != src->type);
+	assert(PARSE_TERM_CLASS != src->type);
+
+	memcpy(dst, src, sizeof(parse_term_t));
+	if (PARSE_TERM_SUBEXPR == src->type) {
+		dst->subexpr.capacity = src->subexpr.count;
+		dst->subexpr.contents
+		    = malloc(dst->subexpr.capacity * sizeof(parse_sequence_t));
+		for (int i = 0; i < dst->subexpr.count; ++i) {
+			deep_copy_sequence(
+			    &dst->subexpr.contents[i], &src->subexpr.contents[i]);
+		}
+	}
+}
+
+static void desugar_plus(parse_term_t *term)
+{
+	parse_sequence_t *alternatives = malloc(sizeof(parse_sequence_t));
+	alternatives[0].count = alternatives[0].capacity = 2;
+	alternatives[0].contents = malloc(2 * sizeof(parse_term_t));
+
+	memcpy(&alternatives[0].contents[0], term, sizeof(parse_term_t));
+	deep_copy_term(&alternatives[0].contents[1], term);
+	alternatives[0].contents[0].quantifier = PARSE_QUANTIFIER_NONE;
+	alternatives[0].contents[1].quantifier = PARSE_QUANTIFIER_STAR;
+
+	term->quantifier = PARSE_QUANTIFIER_NONE;
+	term->type = PARSE_TERM_SUBEXPR;
+	term->subexpr.count = term->subexpr.capacity = 1;
+	term->subexpr.contents = alternatives;
+}
+
+static void desugar_term(parse_term_t *term)
+{
+	switch (term->quantifier) {
+	case PARSE_QUANTIFIER_PLUS:
+		desugar_plus(term);
+		break;
+	case PARSE_QUANTIFIER_NONE:
+	case PARSE_QUANTIFIER_STAR:
+		break;
+	}
+}
 
 void desugar_regex(parse_tree_t *regex)
 {
+	for (int i = 0; i < regex->count; ++i) {
+		for (int j = 0; j < regex->contents[i].count; ++j)
+			desugar_term(&regex->contents[i].contents[j]);
+	}
 }