lib: introduce three new functions call(), loadstring() and loadfile()

Introduce new functions dealing with on-the-fly compilation of code and
execution of functions with different global scope.

The `loadstring()` and `loadfile()` functions will compile the given
ucode source string or ucode file path respectively and return the entry
function of the resulting program.

An optional dictionary specifying parse options may be given as second
argument.

Both functions return `null` on invalid arguments and throw an exception
in case of compilation errors.

The `call()` function allows invoking a given function value with a
different `this` context and/or a different global environment.

Finally refactor the existing `uc_require_ucode()` implementation to
reuse the new `uc_loadfile()` and `uc_call()` implementations and adjust
as well as simplify affected testcases.

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

1 files changed, 166 insertions, 0 deletions

diff --git a/tests/custom/03_stdlib/62_loadfile b/tests/custom/03_stdlib/62_loadfile
new file mode 100644
index 0000000..4926696
--- /dev/null
+++ b/tests/custom/03_stdlib/62_loadfile
@@ -0,0 +1,166 @@
+The `loadfile()` function operates similar to `loadstring()` but reads the
+input to compile from the specified file path instead.
+
+It compiles the given file name into a ucode program and returns the resulting
+entry function.
+
+Throws an exception on compilation or file i/o failure.
+
+Returns the compiled program entry function.
+
+
+Compile a simple program with default options
+
+-- Testcase --
+{%
+	let fn = loadfile('./files/test1.uc');
+	fn();
+%}
+-- End --
+
+-- File test1.uc --
+return 1 + 1;
+-- End --
+
+-- Expect stdout --
+return 1 + 1;
+-- End --
+
+
+Compile a program in raw mode
+
+-- Testcase --
+{%
+	let fn = loadfile('./files/test2.uc', { raw_mode: true });
+	fn();
+%}
+-- End --
+
+-- File test2.uc --
+printf("%d\n", 1 + 1);
+-- End --
+
+-- Expect stdout --
+2
+-- End --
+
+
+Compile a program in template mode
+
+-- Testcase --
+{%
+	let fn = loadfile('./files/test3.uc', { raw_mode: false });
+	fn();
+%}
+-- End --
+
+-- File test3.uc --
+{{ 1 + 1 }}
+-- End --
+
+-- Expect stdout --
+2
+-- End --
+
+
+Override module search path during compilation (import should fail due to empty path)
+
+-- Testcase --
+{%
+	loadfile('./files/test4.uc', {
+		raw_mode: true,
+		module_search_path: []
+	});
+%}
+-- End --
+
+-- File test4.uc --
+import { readfile } from "fs";
+-- End --
+
+-- Expect stderr --
+Runtime error: Unable to compile source file './files/test4.uc':
+
+  | Syntax error: Unable to resolve path for module 'fs'
+  | In line 1, byte 30:
+  |
+  |  `import { readfile } from "fs";`
+  |   Near here -------------------^
+
+In line 5, byte 3:
+
+ `    });`
+       ^-- Near here
+
+
+-- End --
+
+
+Force dynamic loading of unknown extensions at compile time (should succeed)
+
+-- Testcase --
+{%
+	loadfile('./files/test5.uc', {
+		raw_mode: true,
+		force_dynlink_list: [ "doesnotexist" ]
+	});
+
+	print("OK\n");
+%}
+-- End --
+
+-- File test5.uc --
+import foo from "doesnotexist";
+-- End --
+
+-- Expect stdout --
+OK
+-- End --
+
+
+Compiling a syntax error (should fail with syntax error exception)
+
+-- Testcase --
+{%
+	loadfile('./files/test6.uc', { raw_mode: true });
+%}
+-- End --
+
+-- File test6.uc --
+1 +
+-- End --
+
+-- Expect stderr --
+Runtime error: Unable to compile source file './files/test6.uc':
+
+  | Syntax error: Expecting expression
+  | In line 1, byte 5:
+  |
+  |  `1 +`
+  |      ^-- Near here
+
+In line 2, byte 49:
+
+ `    loadfile('./files/test6.uc', { raw_mode: true });`
+  Near here -----------------------------------------^
+
+
+-- End --
+
+
+Test loading precompiled bytecode
+
+-- Testcase --
+{%
+	import { readlink } from 'fs';
+
+	system(`${readlink('/proc/self/exe')} -T, -c -o ./files/test7.uc -e 'Hello world\n'`);
+
+	let fn = loadfile('./files/test7.uc');
+	fn();
+%}
+-- End --
+
+-- Expect stdout --
+Hello world
+-- End --