Modify grammar slighly to simplify parse tree

README

@@ -10,7 +10,7 @@ so here we are.
 This engine is not going to be strictly supporting any standard
 syntax; the expression syntax I intend to support follows.
 
-	regex ::= sequence ( '|' regex )?
+	regex ::= sequence ( '|' sequence )*
 	sequence ::= term+
 	term ::= ( '.' | class | literal | '(' regex ')' ) quantifier?
 	class ::= '[' '^'? literal+ ']'

lib/parser.c

@@ -10,6 +10,7 @@
 
 #define CLASS_START_CAPACITY 4
 #define SEQUENCE_START_CAPACITY 8
+#define PARSE_TREE_START_CAPACITY 4
 
 static bool is_special(char c)
 {
@@ -182,23 +183,37 @@ int parse_expr(const char *input, int rem, parse_tree_t *out)
 {
 	int result, used = 0;
 
-	result = parse_sequence(input + used, rem - used, &out->sequence);
+	out->count = 0;
+	out->capacity = PARSE_TREE_START_CAPACITY;
+	out->alternatives = malloc(out->capacity * sizeof(sequence_t));
+	if (NULL == out->alternatives)
+		return -1;
+
+	result = parse_sequence(input + used, rem - used, &out->alternatives[0]);
 	if (result < 0)
 		return -1;
+	++out->count;
 	used += result;
 
-	if (used < rem && '|' == input[used]) {
+	while (used < rem) {
+		if ('|' != input[used])
+			break;
 		++used;
 
-		out->alternative = malloc(sizeof(parse_tree_t));
+		if (out->count >= out->capacity) {
-		if (NULL == out->alternative)
+			out->capacity *= 2;
+			out->alternatives = realloc(
+			    out->alternatives, out->capacity * sizeof(sequence_t));
+			if (NULL == out->alternatives)
 				return -1;
-		result = parse_expr(input + used, rem - used, out->alternative);
+		}
+
+		result = parse_sequence(
+		    input + used, rem - used, &out->alternatives[out->count]);
 		if (result < 0)
-			return -1;
+			break;
+		++out->count;
 		used += result;
-	} else {
-		out->alternative = NULL;
 	}
 
 	return used;
@@ -232,9 +247,9 @@ static void sequence_free(sequence_t *s)
 
 void parse_tree_free_children(parse_tree_t *t)
 {
-	sequence_free(&t->sequence);
+	if (NULL != t->alternatives) {
-	if (NULL != t->alternative) {
+		for (int i = 0; i < t->count; ++i)
-		parse_tree_free_children(t->alternative);
+			sequence_free(&t->alternatives[i]);
-		free(t->alternative);
+		free(t->alternatives);
 	}
 }

lib/parser.h

@@ -35,8 +35,8 @@ typedef struct {
 } sequence_t;
 
 typedef struct _parse_tree {
-	sequence_t sequence;
+	int count, capacity;
-	struct _parse_tree *alternative;
+	sequence_t *alternatives;
 } parse_tree_t;
 
 typedef struct _term {

tests/parser_tests.c

@@ -8,31 +8,30 @@
 
 #define PARSE_EXPR_STRING(s, r) parse_expr(s, strlen(s), r)
 
-static void a_has_no_alternative(void)
+static void a_has_1_alternative(void)
 {
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("a", &t);
 	ASSERT_NE(-1, result);
-	ASSERT_NULL(t.alternative);
+	ASSERT_EQ(1, t.count);
 	parse_tree_free_children(&t);
 }
 
-static void a_pipe_b_has_alternative(void)
+static void a_pipe_b_has_2_alternatives(void)
 {
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("a|b", &t);
 	ASSERT_NE(-1, result);
-	ASSERT_NOT_NULL(t.alternative);
+	ASSERT_EQ(2, t.count);
 	parse_tree_free_children(&t);
 }
 
-static void a_pipe_b_pipe_c_result_alternative_has_alternative(void)
+static void a_pipe_b_pipe_c_has_3_alternatives(void)
 {
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("a|b|c", &t);
 	ASSERT_NE(-1, result);
-	ASSERT_NOT_NULL(t.alternative);
+	ASSERT_EQ(3, t.count);
-	ASSERT_NOT_NULL(t.alternative->alternative);
 	parse_tree_free_children(&t);
 }
 
@@ -41,11 +40,13 @@ static void a_is_parsed_as_unquantified_literal(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("a", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[0].type);
-	ASSERT_EQ('a', t.sequence.contents[0].literal);
+	ASSERT_EQ('a', t.alternatives[0].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -55,11 +56,13 @@ static void b_is_parsed_as_unquantified_literal(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("b", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[0].type);
-	ASSERT_EQ('b', t.sequence.contents[0].literal);
+	ASSERT_EQ('b', t.alternatives[0].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -69,17 +72,19 @@ static void abc_is_parsed_as_sequence_of_unquantified_literals(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("abc", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(3, t.sequence.len);
+	ASSERT_EQ(3, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[0].type);
-	ASSERT_EQ('a', t.sequence.contents[0].literal);
+	ASSERT_EQ('a', t.alternatives[0].contents[0].literal);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[1].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[1].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[1].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[1].type);
-	ASSERT_EQ('b', t.sequence.contents[1].literal);
+	ASSERT_EQ('b', t.alternatives[0].contents[1].literal);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[2].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[2].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[2].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[2].type);
-	ASSERT_EQ('c', t.sequence.contents[2].literal);
+	ASSERT_EQ('c', t.alternatives[0].contents[2].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -89,10 +94,12 @@ static void dot_is_parsed_as_unquantified_wildcard_term(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING(".", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_WILDCARD, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_WILDCARD, t.alternatives[0].contents[0].type);
 
 	parse_tree_free_children(&t);
 }
@@ -102,11 +109,13 @@ static void backslash_dot_is_parsed_as_unquantified_literal(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("\\.", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[0].type);
-	ASSERT_EQ('.', t.sequence.contents[0].literal);
+	ASSERT_EQ('.', t.alternatives[0].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -116,11 +125,13 @@ static void backslash_backslash_is_parsed_as_unquantified_literal(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("\\\\", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[0].type);
-	ASSERT_EQ('\\', t.sequence.contents[0].literal);
+	ASSERT_EQ('\\', t.alternatives[0].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -130,22 +141,27 @@ static void a_pipe_b_in_parens_is_parsed_as_subexpr_term(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("(a|b)", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_SUBEXPR, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_SUBEXPR, t.alternatives[0].contents[0].type);
 
-	const parse_tree_t *inner = &t.sequence.contents[0].subexpr;
+	const parse_tree_t *inner = &t.alternatives[0].contents[0].subexpr;
-	ASSERT_EQ(1, inner->sequence.len);
+	ASSERT_EQ(2, inner->count);
-	ASSERT_EQ(QUANTIFIER_NONE, inner->sequence.contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, inner->sequence.contents[0].type);
-	ASSERT_EQ('a', inner->sequence.contents[0].literal);
 
-	const parse_tree_t *inner_alt = inner->alternative;
+	ASSERT_EQ(1, inner->alternatives[0].len);
-	ASSERT_EQ(1, inner->sequence.len);
+	ASSERT_EQ(
-	ASSERT_EQ(QUANTIFIER_NONE, inner_alt->sequence.contents[0].quantifier);
+	    QUANTIFIER_NONE, inner->alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, inner_alt->sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, inner->alternatives[0].contents[0].type);
-	ASSERT_EQ('b', inner_alt->sequence.contents[0].literal);
+	ASSERT_EQ('a', inner->alternatives[0].contents[0].literal);
+
+	ASSERT_EQ(1, inner->alternatives[1].len);
+	ASSERT_EQ(
+	    QUANTIFIER_NONE, inner->alternatives[1].contents[0].quantifier);
+	ASSERT_EQ(TERM_TYPE_LITERAL, inner->alternatives[1].contents[0].type);
+	ASSERT_EQ('b', inner->alternatives[1].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -155,19 +171,22 @@ static void a_in_parens_b_is_parsed_as_sequence_with_subexpr_term(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("(a)b", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(2, t.sequence.len);
+	ASSERT_EQ(2, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_SUBEXPR, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_SUBEXPR, t.alternatives[0].contents[0].type);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[1].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[1].quantifier);
-	ASSERT_EQ(TERM_TYPE_LITERAL, t.sequence.contents[1].type);
+	ASSERT_EQ(TERM_TYPE_LITERAL, t.alternatives[0].contents[1].type);
-	ASSERT_EQ('b', t.sequence.contents[1].literal);
+	ASSERT_EQ('b', t.alternatives[0].contents[1].literal);
 
-	const parse_tree_t *inner = &t.sequence.contents[0].subexpr;
+	const parse_tree_t *inner = &t.alternatives[0].contents[0].subexpr;
-	ASSERT_EQ(1, inner->sequence.len);
+	ASSERT_EQ(1, inner->alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, inner->sequence.contents[0].quantifier);
+	ASSERT_EQ(
-	ASSERT_EQ(TERM_TYPE_LITERAL, inner->sequence.contents[0].type);
+	    QUANTIFIER_NONE, inner->alternatives[0].contents[0].quantifier);
-	ASSERT_EQ('a', inner->sequence.contents[0].literal);
+	ASSERT_EQ(TERM_TYPE_LITERAL, inner->alternatives[0].contents[0].type);
+	ASSERT_EQ('a', inner->alternatives[0].contents[0].literal);
 
 	parse_tree_free_children(&t);
 }
@@ -177,10 +196,13 @@ static void dot_star_is_parsed_as_zero_or_more_wildcard(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING(".*", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_ZERO_OR_MORE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(
-	ASSERT_EQ(TERM_TYPE_WILDCARD, t.sequence.contents[0].type);
+	    QUANTIFIER_ZERO_OR_MORE, t.alternatives[0].contents[0].quantifier);
+	ASSERT_EQ(TERM_TYPE_WILDCARD, t.alternatives[0].contents[0].type);
 
 	parse_tree_free_children(&t);
 }
@@ -190,10 +212,13 @@ static void dot_plus_is_parsed_as_one_or_more_wildcard(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING(".+", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_ONE_OR_MORE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(
-	ASSERT_EQ(TERM_TYPE_WILDCARD, t.sequence.contents[0].type);
+	    QUANTIFIER_ONE_OR_MORE, t.alternatives[0].contents[0].quantifier);
+	ASSERT_EQ(TERM_TYPE_WILDCARD, t.alternatives[0].contents[0].type);
 
 	parse_tree_free_children(&t);
 }
@@ -203,10 +228,13 @@ static void dot_question_mark_is_parsed_as_zero_or_one_wildcard(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING(".?", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_ZERO_OR_ONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(
-	ASSERT_EQ(TERM_TYPE_WILDCARD, t.sequence.contents[0].type);
+	    QUANTIFIER_ZERO_OR_ONE, t.alternatives[0].contents[0].quantifier);
+	ASSERT_EQ(TERM_TYPE_WILDCARD, t.alternatives[0].contents[0].type);
 
 	parse_tree_free_children(&t);
 }
@@ -216,14 +244,16 @@ static void a_in_brackets_is_parsed_as_class_containing_only_a(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("[a]", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_CLASS, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_CLASS, t.alternatives[0].contents[0].type);
-	ASSERT_FALSE(t.sequence.contents[0].class.negated);
+	ASSERT_FALSE(t.alternatives[0].contents[0].class.negated);
-	ASSERT_EQ(1, t.sequence.contents[0].class.count);
+	ASSERT_EQ(1, t.alternatives[0].contents[0].class.count);
-	ASSERT_NOT_NULL(t.sequence.contents[0].class.contents);
+	ASSERT_NOT_NULL(t.alternatives[0].contents[0].class.contents);
-	ASSERT_EQ('a', t.sequence.contents[0].class.contents[0]);
+	ASSERT_EQ('a', t.alternatives[0].contents[0].class.contents[0]);
 
 	parse_tree_free_children(&t);
 }
@@ -233,14 +263,16 @@ static void caret_a_in_brackets_parses_as_negated_class(void)
 	parse_tree_t t;
 	const int result = PARSE_EXPR_STRING("[^a]", &t);
 	ASSERT_NE(-1, result);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.alternatives);
 
-	ASSERT_EQ(1, t.sequence.len);
+	ASSERT_EQ(1, t.alternatives[0].len);
-	ASSERT_EQ(QUANTIFIER_NONE, t.sequence.contents[0].quantifier);
+	ASSERT_EQ(QUANTIFIER_NONE, t.alternatives[0].contents[0].quantifier);
-	ASSERT_EQ(TERM_TYPE_CLASS, t.sequence.contents[0].type);
+	ASSERT_EQ(TERM_TYPE_CLASS, t.alternatives[0].contents[0].type);
-	ASSERT_TRUE(t.sequence.contents[0].class.negated);
+	ASSERT_TRUE(t.alternatives[0].contents[0].class.negated);
-	ASSERT_EQ(1, t.sequence.contents[0].class.count);
+	ASSERT_EQ(1, t.alternatives[0].contents[0].class.count);
-	ASSERT_NOT_NULL(t.sequence.contents[0].class.contents);
+	ASSERT_NOT_NULL(t.alternatives[0].contents[0].class.contents);
-	ASSERT_EQ('a', t.sequence.contents[0].class.contents[0]);
+	ASSERT_EQ('a', t.alternatives[0].contents[0].class.contents[0]);
 
 	parse_tree_free_children(&t);
 }
@@ -248,9 +280,9 @@ static void caret_a_in_brackets_parses_as_negated_class(void)
 int main(void)
 {
 	TESTING_BEGIN();
-	a_has_no_alternative();
+	a_has_1_alternative();
-	a_pipe_b_has_alternative();
+	a_pipe_b_has_2_alternatives();
-	a_pipe_b_pipe_c_result_alternative_has_alternative();
+	a_pipe_b_pipe_c_has_3_alternatives();
 	a_is_parsed_as_unquantified_literal();
 	b_is_parsed_as_unquantified_literal();
 	abc_is_parsed_as_sequence_of_unquantified_literals();