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2024 Day 3 refactoring

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This commit is contained in:
Jeremy Kaplan 2024-12-02 22:32:09 -08:00
commit c9793c76cd
1 changed files with 28 additions and 19 deletions
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47
2024/src/day03.zig
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@ -49,17 +49,18 @@ const Memory = struct {
fn next_mul(self: *Memory) ?Mul {
while (self.pos < self.text.len) {
self.pos += std.mem.indexOf(u8, self.text[self.pos..], "mul(") orelse return null;
self.pos += consume(self.text[self.pos..], "mul(").?;
const a = parsePrefixInt(self.text[self.pos..]) orelse continue;
self.pos += a.chars;
self.pos += consumeLiteral(self.text[self.pos..], "mul(").?;
self.pos += consume(self.text[self.pos..], ",") orelse continue;
const a = consumeInt(self.text[self.pos..]) orelse continue;
self.pos += a.chars.len;
const b = parsePrefixInt(self.text[self.pos..]) orelse continue;
self.pos += b.chars;
self.pos += consumeLiteral(self.text[self.pos..], ",") orelse continue;
self.pos += consume(self.text[self.pos..], ")") orelse continue;
const b = consumeInt(self.text[self.pos..]) orelse continue;
self.pos += b.chars.len;
self.pos += consumeLiteral(self.text[self.pos..], ")") orelse continue;
return .{ .a = a.value, .b = b.value };
}
@ -68,27 +69,28 @@ const Memory = struct {
fn next_instruction(self: *Memory) ?Instruction {
while (self.pos < self.text.len) {
if (consume(self.text[self.pos..], "do()")) |n| {
if (consumeLiteral(self.text[self.pos..], "do()")) |n| {
self.pos += n;
return Instruction.do;
}
if (consume(self.text[self.pos..], "don't()")) |n| {
if (consumeLiteral(self.text[self.pos..], "don't()")) |n| {
self.pos += n;
return Instruction.dont;
}
if (consume(self.text[self.pos..], "mul(")) |n| {
if (consumeLiteral(self.text[self.pos..], "mul(")) |n| {
self.pos += n;
const a = parsePrefixInt(self.text[self.pos..]) orelse continue;
self.pos += a.chars;
self.pos += consume(self.text[self.pos..], ",") orelse continue;
const a = consumeInt(self.text[self.pos..]) orelse continue;
self.pos += a.chars.len;
const b = parsePrefixInt(self.text[self.pos..]) orelse continue;
self.pos += b.chars;
self.pos += consumeLiteral(self.text[self.pos..], ",") orelse continue;
self.pos += consume(self.text[self.pos..], ")") orelse continue;
const b = consumeInt(self.text[self.pos..]) orelse continue;
self.pos += b.chars.len;
self.pos += consumeLiteral(self.text[self.pos..], ")") orelse continue;
return Instruction{ .mul = .{ .a = a.value, .b = b.value } };
}
@ -99,14 +101,21 @@ const Memory = struct {
}
};
fn consume(text: []const u8, want: []const u8) ?usize {
fn Match(comptime T: type) type {
return struct {
value: T,
chars: []const u8,
};
}
fn consumeLiteral(text: []const u8, want: []const u8) ?usize {
if (std.mem.startsWith(u8, text, want)) {
return want.len;
}
return null;
}
fn parsePrefixInt(s: []u8) ?struct { value: u32, chars: usize } {
fn consumeInt(s: []u8) ?Match(u32) {
var idx: usize = 0;
var value: u32 = 0;
@ -117,7 +126,7 @@ fn parsePrefixInt(s: []u8) ?struct { value: u32, chars: usize } {
}
if (idx > 0) {
return .{ .value = value, .chars = idx };
return .{ .value = value, .chars = s[0..idx] };
}
return null;
}