treewide: rewrite ucode interpreter

Replace the former AST walking interpreter implementation with a single pass
bytecode compiler and a corresponding virtual machine.

The rewrite lays the groundwork for a couple of improvements with will be
subsequently implemented:

 - Ability to precompile ucode sources into binary byte code
 - Strippable debug information
 - Reduced runtime memory usage

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

1 files changed, 120 insertions, 0 deletions

diff --git a/compiler.h b/compiler.h
new file mode 100644
index 0000000..53ff987
--- /dev/null
+++ b/compiler.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2020-2021 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.
+ */
+
+#ifndef __COMPILER_H_
+#define __COMPILER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef JSONC
+	#include <json.h>
+#else
+	#include <json-c/json.h>
+#endif
+
+#include "source.h"
+#include "object.h"
+#include "lexer.h"
+#include "util.h"
+
+typedef enum {
+	P_NONE,
+
+	P_COMMA,	/* , */
+
+	P_ASSIGN,	/* = += -= *= /= %= <<= >>= &= ^= |= */
+
+	P_TERNARY,	/* ?: */
+
+	P_OR,		/* || */
+	P_AND,		/* && */
+	P_BOR,		/* | */
+	P_BXOR,		/* ^ */
+	P_BAND,		/* & */
+
+	P_EQUAL,	/* === !== == != */
+	P_COMPARE,	/* < <= > >= in */
+
+	P_SHIFT,	/* << >> */
+
+	P_ADD,		/* + - */
+	P_MUL,		/* * / % */
+
+	P_UNARY,	/* ! ~ +… -… ++… --… */
+
+	P_INC,		/* …++ …-- */
+
+	P_CALL,		/* ….…, …[…], …(…) */
+
+	P_PRIMARY	/* (…) */
+} uc_precedence_t;
+
+struct uc_patchlist {
+	struct uc_patchlist *parent;
+	size_t count, *entries;
+};
+
+typedef struct uc_patchlist uc_patchlist;
+
+typedef struct {
+	json_object *name;
+	ssize_t depth;
+	size_t from;
+	bool captured;
+} uc_local;
+
+typedef struct {
+	json_object *name;
+	size_t index;
+	bool local;
+} uc_upval;
+
+uc_declare_vector(uc_locals, uc_local);
+uc_declare_vector(uc_upvals, uc_upval);
+uc_declare_vector(uc_jmplist, size_t);
+
+typedef struct {
+	uc_parse_config *config;
+	uc_lexer lex;
+	uc_token prev, curr;
+	bool synchronizing;
+	char *error;
+} uc_parser;
+
+struct uc_compiler {
+	struct uc_compiler *parent;
+	uc_locals locals;
+	uc_upvals upvals;
+	uc_patchlist *patchlist;
+	uc_function *function;
+	uc_parser *parser;
+	size_t scope_depth, current_srcpos, last_insn;
+	bool statement_emitted;
+};
+
+typedef struct uc_compiler uc_compiler;
+
+typedef struct {
+	void (*prefix)(uc_compiler *, bool);
+	void (*infix)(uc_compiler *, bool);
+	uc_precedence_t precedence;
+} uc_parse_rule;
+
+uc_function *uc_compile(uc_parse_config *config, uc_source *source, char **errp);
+
+#endif /* __COMPILER_H_ */