compiler: add import statement support for dynamic extensions

Utilize the new I_DYNLINK vm opcode to support import statements referring
to dynamic extension modules.

During compilation, the compiler will try to infer the type of the imported
module from the resolved file path; if it ends with `.so`, the module is
assumed to by a dynamic extension and loading/binding of the module is
deferred to runtime using I_DYNLINK opcodes.

Additionally, the `-c` cli option gained support for a new compiler flag
`dynlink=...` which allows forcing a particular module name expression
to be treated as dynamic extension. This is useful to e.g. force resolving
`import { x } from "foo"` to a dynamic extension `foo.so` loaded at runtime
even if a plain `foo.uc` exists in the search path during compilation or if
no such module is available at build time.

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

1 files changed, 68 insertions, 2 deletions

diff --git a/compiler.c b/compiler.c
index 7fd4da2..1199d82 100644
--- a/compiler.c
+++ b/compiler.c
@@ -3330,6 +3330,68 @@ uc_compiler_acquire_source(uc_compiler_t *compiler, const char *path)
 }
 
 static bool
+uc_compiler_compile_dynload(uc_compiler_t *compiler, const char *name, uc_value_t *imports)
+{
+	uc_value_t *modname = ucv_string_new(name);
+	size_t i, n_imports;
+	uc_value_t *import;
+
+	for (i = 0, n_imports = 0; i < ucv_array_length(imports); i++) {
+		import = ucv_array_get(imports, i);
+
+		if (ucv_boolean_get(import)) {
+			uc_compiler_emit_insn(compiler, 0, I_DYNLOAD);
+			uc_compiler_emit_u32(compiler, 0, 0);
+			uc_compiler_emit_constant_index(compiler, 0, modname);
+		}
+		else {
+			n_imports++;
+		}
+	}
+
+	if (n_imports > 0) {
+		uc_compiler_emit_insn(compiler, 0, I_DYNLOAD);
+		uc_compiler_emit_u32(compiler, 0, n_imports | ((compiler->upvals.count - n_imports) << 16));
+		uc_compiler_emit_constant_index(compiler, 0, modname);
+
+		for (i = 0; i < ucv_array_length(imports); i++) {
+			import = ucv_get(ucv_array_get(imports, i));
+
+			if (!import)
+				import = ucv_string_new("default");
+
+			if (!ucv_boolean_get(import))
+				uc_compiler_emit_constant_index(compiler, 0, import);
+
+			ucv_put(import);
+		}
+	}
+
+	ucv_put(modname);
+
+	return true;
+}
+
+static bool
+uc_compiler_is_dynlink_module(uc_compiler_t *compiler, const char *name, const char *path)
+{
+	uc_search_path_t *dynlink_list = &compiler->parser->config->force_dynlink_list;
+	size_t i;
+	char *p;
+
+	for (i = 0; i < dynlink_list->count; i++)
+		if (!strcmp(dynlink_list->entries[i], name))
+			return true;
+
+	if (!path)
+		return false;
+
+	p = strrchr(path, '.');
+
+	return (p && !strcmp(p, ".so"));
+}
+
+static bool
 uc_compiler_compile_module(uc_compiler_t *compiler, const char *name, uc_value_t *imports)
 {
 	uc_source_t *source;
@@ -3341,7 +3403,10 @@ uc_compiler_compile_module(uc_compiler_t *compiler, const char *name, uc_value_t
 
 	path = uc_compiler_resolve_module_path(compiler, name);
 
-	if (path) {
+	if (uc_compiler_is_dynlink_module(compiler, name, path)) {
+		res = uc_compiler_compile_dynload(compiler, name, imports);
+	}
+	else if (path) {
 		source = uc_compiler_acquire_source(compiler, path);
 
 		if (source) {
@@ -3361,6 +3426,8 @@ uc_compiler_compile_module(uc_compiler_t *compiler, const char *name, uc_value_t
 
 			res = false;
 		}
+
+		uc_source_put(source);
 	}
 	else {
 		uc_compiler_syntax_error(compiler, compiler->parser->curr.pos,
@@ -3369,7 +3436,6 @@ uc_compiler_compile_module(uc_compiler_t *compiler, const char *name, uc_value_t
 		return false;
 	}
 
-	uc_source_put(source);
 	free(path);
 
 	return res;