| ... | ... | @@ -10,9 +10,17 @@ const lossyCast = std.math.lossyCast; |
| 10 | 10 | |
| 11 | 11 | pub const default_max_depth = 3; |
| 12 | 12 | |
| 13 | pub const Alignment = enum { |
| 14 | Left, |
| 15 | Center, |
| 16 | Right, |
| 17 | }; |
| 18 | |
| 13 | 19 | pub const FormatOptions = struct { |
| 14 | 20 | precision: ?usize = null, |
| 15 | 21 | width: ?usize = null, |
| 22 | alignment: ?Alignment = null, |
| 23 | fill: u8 = ' ', |
| 16 | 24 | }; |
| 17 | 25 | |
| 18 | 26 | fn nextArg(comptime used_pos_args: *u32, comptime maybe_pos_arg: ?comptime_int, comptime next_arg: *comptime_int) comptime_int { |
| ... | ... | @@ -26,6 +34,18 @@ fn nextArg(comptime used_pos_args: *u32, comptime maybe_pos_arg: ?comptime_int, |
| 26 | 34 | } |
| 27 | 35 | } |
| 28 | 36 | |
| 37 | fn peekIsAlign(comptime fmt: []const u8) bool { |
| 38 | // Should only be called during a state transition to the format segment. |
| 39 | std.debug.assert(fmt[0] == ':'); |
| 40 | |
| 41 | inline for (([_]u8{ 1, 2 })[0..]) |i| { |
| 42 | if (fmt.len > i and (fmt[i] == '<' or fmt[i] == '^' or fmt[i] == '>')) { |
| 43 | return true; |
| 44 | } |
| 45 | } |
| 46 | return false; |
| 47 | } |
| 48 | |
| 29 | 49 | /// Renders fmt string with args, calling output with slices of bytes. |
| 30 | 50 | /// If `output` returns an error, the error is returned from `format` and |
| 31 | 51 | /// `output` is not called again. |
| ... | ... | @@ -46,6 +66,7 @@ pub fn format( |
| 46 | 66 | Positional, |
| 47 | 67 | CloseBrace, |
| 48 | 68 | Specifier, |
| 69 | FormatFillAndAlign, |
| 49 | 70 | FormatWidth, |
| 50 | 71 | FormatPrecision, |
| 51 | 72 | Pointer, |
| ... | ... | @@ -92,7 +113,7 @@ pub fn format( |
| 92 | 113 | state = .Pointer; |
| 93 | 114 | }, |
| 94 | 115 | ':' => { |
| 95 | | state = .FormatWidth; |
| 116 | state = if (comptime peekIsAlign(fmt[i..])) State.FormatFillAndAlign else State.FormatWidth; |
| 96 | 117 | specifier_end = i; |
| 97 | 118 | }, |
| 98 | 119 | '0'...'9' => { |
| ... | ... | @@ -139,7 +160,7 @@ pub fn format( |
| 139 | 160 | .Specifier => switch (c) { |
| 140 | 161 | ':' => { |
| 141 | 162 | specifier_end = i; |
| 142 | | state = .FormatWidth; |
| 163 | state = if (comptime peekIsAlign(fmt[i..])) State.FormatFillAndAlign else State.FormatWidth; |
| 143 | 164 | }, |
| 144 | 165 | '}' => { |
| 145 | 166 | const arg_to_print = comptime nextArg(&used_pos_args, maybe_pos_arg, &next_arg); |
| ... | ... | @@ -158,6 +179,24 @@ pub fn format( |
| 158 | 179 | }, |
| 159 | 180 | else => {}, |
| 160 | 181 | }, |
| 182 | // Only entered if the format string contains a fill/align segment. |
| 183 | .FormatFillAndAlign => switch (c) { |
| 184 | '<' => { |
| 185 | options.alignment = Alignment.Left; |
| 186 | state = .FormatWidth; |
| 187 | }, |
| 188 | '^' => { |
| 189 | options.alignment = Alignment.Center; |
| 190 | state = .FormatWidth; |
| 191 | }, |
| 192 | '>' => { |
| 193 | options.alignment = Alignment.Right; |
| 194 | state = .FormatWidth; |
| 195 | }, |
| 196 | else => { |
| 197 | options.fill = c; |
| 198 | }, |
| 199 | }, |
| 161 | 200 | .FormatWidth => switch (c) { |
| 162 | 201 | '0'...'9' => { |
| 163 | 202 | if (options.width == null) { |
| ... | ... | @@ -1571,3 +1610,7 @@ test "positional" { |
| 1571 | 1610 | test "positional with specifier" { |
| 1572 | 1611 | try testFmt("10.0", "{0d:.1}", f64(9.999)); |
| 1573 | 1612 | } |
| 1613 | |
| 1614 | test "positional/alignment/width/precision" { |
| 1615 | try testFmt("10.0", "{0d: >3.1}", f64(9.999)); |
| 1616 | } |
Marc Tiehuis <marc@tiehu.is> 2019-06-25 17:11:04+12:00
std