util: Create string_view tool to optimize memory usage

We are allocating heap memory to create tokens value, we can minimize the
number of allocations if we start using string_view.

We have other problems, right now the tokens value ownership are quite
unclear once the AST nodes also share the memory allocation done by
token_get_next_token function.

It's important to clarify we also have memory leaks on the current
implementation.  Hence, we are going to start using string_view to make
the memory management easier. :^)

Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>

6 files changed, 207 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 09fff70..ec8e003 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 pipac
 build
 *.o
+test/*_test
diff --git a/Makefile b/Makefile
index 5ff8463..4417423 100644
--- a/Makefile
+++ b/Makefile
@@ -15,9 +15,14 @@ $(TARGET): $(BUILD_DIR) $(OBJS)
 $(BUILD_DIR):
 	@mkdir -p $@
 
+.PHONY: test
+test: $(TARGET)
+	$(MAKE) -C test
+
 .PHONY: clean
 clean:
-	@rm -rf $(BUILD_DIR) $(TARGET)
+	$(RM) -rf $(BUILD_DIR) $(TARGET)
+	$(MAKE) -C test clean
 
 $(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
 	$(CC) $(CFLAGS) -c $< -o $@
diff --git a/src/string_view.c b/src/string_view.c
new file mode 100644
index 0000000..d511e63
--- /dev/null
+++ b/src/string_view.c
@@ -0,0 +1,49 @@
+/*
+* Copyright (C) 2023 Johnny Richard
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#include "string_view.h"
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+string_view_t
+string_view_new(const char *str, int size)
+{
+  assert(str);
+
+  return (string_view_t) {
+    .size = size,
+    .str = str
+  };
+}
+
+string_view_t
+string_view_from_str(const char *str)
+{
+  return string_view_new(str, strlen(str));
+}
+
+bool
+string_view_to_str(string_view_t *sv, char *ret)
+{
+  return sprintf(ret, SVFMT, SVARG(sv)) < 0;
+}
+
+bool
+string_view_eq(string_view_t a, string_view_t b)
+{
+  return a.size == b.size && memcmp(a.str, b.str, a.size) == 0;
+}
diff --git a/src/string_view.h b/src/string_view.h
new file mode 100644
index 0000000..41094a2
--- /dev/null
+++ b/src/string_view.h
@@ -0,0 +1,38 @@
+/*
+* Copyright (C) 2023 Johnny Richard
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#ifndef STRING_VIEW
+#define STRING_VIEW
+
+#define SVFMT "%.*s"
+#define SVARG(sv) (sv)->size, (sv)->str
+
+#include <stdbool.h>
+
+typedef struct string_view_t {
+  const char *str;
+  int         size;
+} string_view_t;
+
+string_view_t string_view_new(const char *str, int size);
+
+string_view_t string_view_from_str(const char *str);
+
+bool string_view_to_str(string_view_t *sv, char *ret);
+
+bool string_view_eq(string_view_t a, string_view_t b);
+
+#endif /* STRING_VIEW */
diff --git a/test/Makefile b/test/Makefile
new file mode 100644
index 0000000..7a37dfe
--- /dev/null
+++ b/test/Makefile
@@ -0,0 +1,16 @@
+SRCS        := $(wildcard *_test.c)
+OBJS        := $(patsubst %_test.c, %_test.o, $(SRCS))
+CFLAGS      := -I../src
+TESTS       := $(patsubst %_test.c, %_test, $(SRCS))
+EXEC_TESTS  := $(patsubst %_test, ./%_test, $(TESTS))
+
+.PHONY: all
+all: munit.o $(TESTS)
+	$(EXEC_TESTS)
+
+.PHONY: clean
+clean:
+	$(RM) *.o *_test
+
+string_view_test: munit.o string_view_test.o ../build/string_view.o
+	$(CC) $? $(CFLAGS) -o $@
diff --git a/test/string_view_test.c b/test/string_view_test.c
new file mode 100644
index 0000000..130ec2c
--- /dev/null
+++ b/test/string_view_test.c
@@ -0,0 +1,97 @@
+/*
+* Copyright (C) 2023 Johnny Richard
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#define MUNIT_ENABLE_ASSERT_ALIASES
+#include "munit.h"
+#include "string_view.h"
+
+static MunitResult
+test_create_new(const  MunitParameter params[],
+                void  *user_data_or_fixture)
+{
+  char *str = "hello world";
+  string_view_t sv = string_view_new(str, strlen(str));
+
+  assert_string_equal("hello world", (char *) sv.str);
+  assert_int(sv.size, ==, strlen(str));
+
+  return MUNIT_OK;
+}
+
+static MunitResult
+test_from_str(const  MunitParameter params[],
+                void  *user_data_or_fixture)
+{
+  char *str = "hello world";
+
+  string_view_t sv = string_view_from_str(str);
+
+  assert_string_equal(str, (char *) sv.str);
+  assert_int(sv.size, ==, strlen(str));
+
+  return MUNIT_OK;
+}
+
+static MunitResult
+test_to_str(const  MunitParameter params[],
+             void  *user_data_or_fixture)
+{
+  char *str = "hello world";
+
+  string_view_t sv = string_view_new(str, 5);
+
+  char actual[sv.size + 1];
+  string_view_to_str(&sv, actual);
+
+  assert_string_equal(actual, "hello");
+
+  return MUNIT_OK;
+}
+
+static MunitResult
+test_eq(const  MunitParameter params[],
+        void  *user_data_or_fixture)
+{
+  string_view_t a = string_view_from_str("hello");
+  string_view_t b = string_view_from_str("world");
+
+  assert_false(string_view_eq(a, b));
+
+  b = string_view_from_str("hello");
+
+  assert_true(string_view_eq(a, b));
+
+  return MUNIT_OK;
+}
+
+static MunitTest tests[] = {
+  { "/test_create_new", test_create_new, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
+  { "/test_from_str", test_from_str, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
+  { "/test_to_str", test_to_str, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
+  { "/test_eq", test_eq, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
+  { NULL, NULL, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL }
+};
+
+static const MunitSuite suite = {
+  "/string_view", tests, NULL, 1, MUNIT_SUITE_OPTION_NONE
+};
+
+int
+main(int argc, char *argv[])
+{
+  return munit_suite_main(&suite, NULL, argc, argv);
+  return EXIT_SUCCESS;
+}