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import std.stdio;
import std.string;
import parser;
import chunk;
import dbg;
enum FunctionType {
FUNCTION,
SCRIPT,
}
struct Local {
Symbol sym;
int depth;
}
class Compiler {
Function func;
FunctionType type;
Parser* parser;
Local[] locals;
int scopeDepth;
Form current;
Form previous;
Form outer;
int outerIdx;
void advance() {
previous = current;
/*
if (outer.type != FormType.EOF && outerIdx < outer) {
current = parser.parseForm();
} else {
}
*/
current = parser.parseForm();
}
void compileNil(Form form) {
form.compile(func);
advance();
}
void compileAtom(Form form) {
form.compile(func);
advance();
}
void compileAdd(Form[] args) {
resolve(args[0]);
// (+ n) always returns n
if (args.length == 1) {
return;
}
for (int i = 1; i < args.length; i++) {
resolve(args[i]);
func.chunk.writeOp(OpCode.OP_ADD, current.line);
}
}
void compileNegate(Form arg) {
resolve(arg);
func.chunk.writeOp(OpCode.OP_NEGATE, current.line);
}
void compileSubtract(Form[] args) {
resolve(args[0]);
for (int i = 1; i < args.length; i++) {
resolve(args[i]);
func.chunk.writeOp(OpCode.OP_SUBTRACT, current.line);
}
}
void compileLess(Form[] args) {
if (args.length != 2) {
writeln("'<' requires 2 arguments");
return;
}
resolve(args[0]);
resolve(args[1]);
func.chunk.writeOp(OpCode.OP_LESS, current.line);
}
void compileCons(Form form) {
Cons cons = cast(Cons)form;
Form head = cons.head;
if (head.type != FormType.SYMBOL) {
writeln("cons must start with a symbol");
return;
}
Symbol sym = cast(Symbol)head;
switch (sym.name) {
case "+":
compileAdd(cons.tail);
break;
case "-":
if (cons.tail.length == 1) {
compileNegate(cons.tail[0]);
} else {
compileSubtract(cons.tail);
}
break;
case "<":
compileLess(cons.tail);
break;
default:
writefln("unsure how to compile %s", sym.name);
advance();
break;
}
}
void resolve(Form form) {
write("resolving: ");
printForm(form);
switch(form.type) {
case FormType.ATOM:
this.compileAtom(form);
break;
case FormType.CONS:
this.compileCons(form);
break;
case FormType.NIL:
this.compileNil(form);
break;
default:
write("not sure how to resolve: ");
printForm(form);
advance();
break;
}
}
Function compile() {
writeln("compiling");
advance();
while(current.type != FormType.EOF) {
resolve(current);
}
return finish();
}
Function finish() {
//emitReturn();
writeln("finishing the compiler!");
this.func.chunk.writeOp(OpCode.OP_RETURN, current.line);
writeln("wrote a return code");
return func;
}
this(FunctionType type, Parser* parser) {
this.parser = parser;
this.func = new Function();
this.type = type;
locals ~= Local(new Symbol("", -1), 0);
}
}
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