102 lines
2.3 KiB
Zig
102 lines
2.3 KiB
Zig
const math = @import("./math.zig");
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pub const IntParseError = math.CheckedArithmeticError || ParseError;
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pub const ParseError = error {
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BadSyntax,
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};
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pub fn parse_float(comptime bits: comptime_int, utf8: []const u8) ParseError!math.Float(bits) {
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// ""
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if (utf8.len == 0) return error.BadSyntax;
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const is_negative = utf8[0] == '-';
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// "-"
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if (is_negative and (utf8.len == 1)) return error.BadSyntax;
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const negative_offset = @boolToInt(is_negative);
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var has_decimal = utf8[negative_offset] == '.';
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// "-."
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if (has_decimal and (utf8.len == 2)) return error.BadSyntax;
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const Float = math.Float(bits);
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var result: Float = 0;
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var factor: Float = 1;
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for (utf8[0 .. negative_offset + @boolToInt(has_decimal)]) |code| switch (code) {
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'.' => {
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if (has_decimal) return error.BadSyntax;
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has_decimal = true;
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},
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9' => {
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if (has_decimal) factor /= 10.0;
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result = ((result * 10.0) + @intToFloat(Float, code - '0'));
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},
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else => return error.BadSyntax,
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};
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return result * factor;
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}
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pub fn parse_signed(comptime bits: comptime_int, utf8: []const u8) IntParseError!math.Unsigned(bits) {
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// ""
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if (utf8.len == 0) return error.BadSyntax;
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const is_negative = utf8[0] == '-';
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// "-"
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if (is_negative and (utf8.len == 1)) return error.BadSyntax;
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var result: math.Unsigned(bits) = 0;
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{
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var index: usize = 0;
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while (index < utf8.len) : (index += 1) {
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const code = utf8[index];
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switch (code) {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9' =>
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result = try math.checked_add(try math.checked_mul(result, 10), try math.checked_sub(code, '0')),
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else => return error.BadSyntax,
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}
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}
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}
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return result;
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}
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pub fn parse_unsigned(comptime bits: comptime_int, utf8: []const u8) IntParseError!math.Unsigned(bits) {
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// ""
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if (utf8.len == 0) return error.BadSyntax;
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// "-..."
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if (utf8[0] == '-') return error.BadSyntax;
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var result: math.Unsigned(bits) = 0;
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{
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var index: usize = 0;
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while (index < utf8.len) : (index += 1) {
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const code = utf8[index];
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switch (code) {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9' =>
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result = try math.checked_add(try math.checked_mul(result, 10), try math.checked_sub(code, '0')),
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else => return error.BadSyntax,
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}
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}
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}
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return result;
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}
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