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const std = @import("std");
const parse = @import("parser.zig");
pub const Generator = struct {
root: []const parse.NodeStmt,
allocator: std.mem.Allocator,
code: std.ArrayList(u8),
pub fn init(allocator: std.mem.Allocator, stmts: []const parse.NodeStmt) Generator {
return .{
.root = stmts,
.allocator = allocator,
.code = std.ArrayList(u8).init(allocator),
};
}
pub fn deinit(self: *Generator) void {
self.code.deinit();
}
fn genExit(self: *Generator, expr: parse.NodeExpr) !void {
const newCode =
switch (expr) {
.intLit => try std.fmt.allocPrint(self.allocator,
\\ mov rax, 60
\\ mov rdi, {d}
\\ syscall
\\
, .{
expr.intLit.intlit.intLit,
}),
.ident => try std.fmt.allocPrint(self.allocator,
\\ mov rax, 60
\\ mov rdi, [{s}]
\\ syscall
\\
, .{
expr.ident.ident.ident,
}),
};
try self.code.appendSlice(newCode);
self.allocator.free(newCode);
}
fn genValue(self: *Generator, value: parse.NodeValue) !void {
const str = try std.fmt.allocPrint(self.allocator,
\\section .data
\\ {s}: dw {d}
\\
, .{ value.ident.ident, switch (value.value) {
.intLit => value.value.intLit.intlit.intLit,
else => return error.NotImplemented,
} });
defer self.allocator.free(str);
try self.code.insertSlice(0, str);
}
fn genAssign(self: *Generator, assign: parse.NodeAssign) !void {
const newCode =
switch (assign.value) {
.intLit => try std.fmt.allocPrint(self.allocator,
\\ mov rax, {d}
\\ mov [{s}], rax
\\
, .{
assign.value.intLit.intlit.intLit,
assign.ident.ident,
}),
.ident => try std.fmt.allocPrint(self.allocator,
\\ mov rax, [{s}]
\\ mov [{s}], rax
\\
, .{
assign.value.ident.ident.ident,
assign.ident.ident,
}),
};
try self.code.appendSlice(newCode);
self.allocator.free(newCode);
}
pub fn generate(self: *Generator) ![]const u8 {
try self.code.appendSlice(
\\section .text
\\ global _start
\\_start:
\\
);
for (self.root) |stmt| {
switch (stmt) {
.exit => try self.genExit(stmt.exit.expr),
.value => try self.genValue(stmt.value),
.assign => try self.genAssign(stmt.assign),
}
}
return self.code.items;
}
};
test "Codegen exit" {
const tok = @import("tokenize.zig");
const expect = std.testing.expect;
const src = "exit 120;";
var tokenizer = tok.Tokenizer.init(std.testing.allocator, src);
defer tokenizer.deinit();
const toks = try tokenizer.tokenize();
var parser = parse.Parser.init(std.testing.allocator, toks);
defer parser.deinit();
const parseTree = try parser.parse();
var gen = Generator.init(std.testing.allocator, parseTree);
defer gen.deinit();
const actual = try gen.generate();
const expected =
\\section .text
\\ global _start
\\_start:
\\ mov rax, 60
\\ mov rdi, 120
\\ syscall
\\
;
try expect(std.mem.eql(u8, actual, expected));
}
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