examples: add libucode usage examples

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 104 insertions, 0 deletions

diff --git a/examples/native-function.c b/examples/native-function.c
new file mode 100644
index 0000000..89b3d15
--- /dev/null
+++ b/examples/native-function.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2021 Jo-Philipp Wich <jo@mein.io>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+
+#include <ucode/compiler.h>
+#include <ucode/lib.h>
+#include <ucode/vm.h>
+
+
+#define MULTILINE_STRING(...) #__VA_ARGS__
+
+static const char *program = MULTILINE_STRING(
+	{%
+		print("add() = " + add(5, 3.1, 2) + "\n");
+		print("multiply() = " + multiply(7.3, 5) + "\n");
+	%}
+);
+
+static uc_parse_config_t config = {
+	.strict_declarations = false,
+	.lstrip_blocks = true,
+	.trim_blocks = true
+};
+
+static uc_value_t *
+multiply_two_numbers(uc_vm_t *vm, size_t nargs)
+{
+	uc_value_t *x = uc_get_arg(0);
+	uc_value_t *y = uc_get_arg(1);
+
+	return ucv_double_new(ucv_to_double(x) * ucv_to_double(y));
+}
+
+static uc_value_t *
+add_all_numbers(uc_vm_t *vm, size_t nargs)
+{
+	double res = 0.0;
+
+	for (size_t n = 0; n < nargs; n++)
+		res += ucv_to_double(uc_get_arg(n));
+
+	return ucv_double_new(res);
+}
+
+int main(int argc, char **argv)
+{
+	int exit_code = 0;
+
+	/* create a source buffer containing the program code */
+	uc_source_t *src = uc_source_new_buffer("my program", strdup(program), strlen(program));
+
+	/* compile source buffer into function */
+	char *syntax_error = NULL;
+	uc_function_t *progfunc = uc_compile(&config, src, &syntax_error);
+
+	/* release source buffer */
+	uc_source_put(src);
+
+	/* check if compilation failed */
+	if (!progfunc) {
+		fprintf(stderr, "Failed to compile program: %s\n", syntax_error);
+
+		return 1;
+	}
+
+	/* initialize VM context */
+	uc_vm_t vm = { 0 };
+	uc_vm_init(&vm, &config);
+
+	/* load standard library into global VM scope */
+	uc_load_stdlib(uc_vm_scope_get(&vm));
+
+	/* register our native functions as "add" and "multiply" */
+	uc_add_function(uc_vm_scope_get(&vm), "add", add_all_numbers);
+	uc_add_function(uc_vm_scope_get(&vm), "multiply", multiply_two_numbers);
+
+	/* execute program function */
+	int return_code = uc_vm_execute(&vm, progfunc, NULL);
+
+	/* handle return status */
+	if (return_code == ERROR_COMPILE || return_code == ERROR_RUNTIME) {
+		printf("An error occurred while running the program\n");
+		exit_code = 1;
+	}
+
+	/* free VM context */
+	uc_vm_free(&vm);
+
+	return exit_code;
+}