math: Allow --scale=max

CHANGELOG.md

@@ -18,6 +18,7 @@
 - The default escape delay (to differentiate between the escape key and an alt-combination) has been reduced to 30ms, down from 300ms for the default mode and 100ms for vi-mode (#3904).
 - In the interest of consistency, `builtin -q` and `command -q` can now be used to query if a builtin or command exists (#5631).
 - The `path_helper` on macOS now only runs in login shells, matching the bash implementation.
+- `math` now accepts `--scale=max` for the maximum scale (#5579).
 
 ---
 

doc_src/math.txt

@@ -17,7 +17,7 @@ Keep in mind that parameter expansion takes before expressions are evaluated. Th
 
 The following options are available:
 
-- `-sN` or `--scale=N` sets the scale of the result. `N` must be an integer. A scale of zero causes results to be rounded down to the nearest integer. So `3/2` returns `1` rather than `2` which `1.5` would normally round to. This is for compatibility with `bc` which was the basis for this command prior to fish 3.0.0. Scale values greater than zero causes the result to be rounded using the usual rules to the specified number of decimal places.
+- `-sN` or `--scale=N` sets the scale of the result. `N` must be an integer or the word "max" for the maximum scale. A scale of zero causes results to be rounded down to the nearest integer. So `3/2` returns `1` rather than `2` which `1.5` would normally round to. This is for compatibility with `bc` which was the basis for this command prior to fish 3.0.0. Scale values greater than zero causes the result to be rounded using the usual rules to the specified number of decimal places.
 
 \subsection return-values Return Values
 

src/builtin_math.cpp

@@ -48,11 +48,16 @@ static int parse_cmd_opts(math_cmd_opts_t &opts, int *optind,  //!OCLINT(high nc
     while ((opt = w.wgetopt_long(argc, argv, short_options, long_options, NULL)) != -1) {
         switch (opt) {
             case 's': {
-                opts.scale = fish_wcstoi(w.woptarg);
-                if (errno || opts.scale < 0 || opts.scale > 15) {
-                    streams.err.append_format(_(L"%ls: '%ls' is not a valid scale value\n"), cmd,
-                                              w.woptarg);
-                    return STATUS_INVALID_ARGS;
+                // "max" is the special value that tells us to pick the maximum scale.
+                if (wcscmp(w.woptarg, L"max") == 0) {
+                    opts.scale = 15;
+                } else {
+                    opts.scale = fish_wcstoi(w.woptarg);
+                    if (errno || opts.scale < 0 || opts.scale > 15) {
+                        streams.err.append_format(_(L"%ls: '%ls' is not a valid scale value\n"), cmd,
+                                                  w.woptarg);
+                        return STATUS_INVALID_ARGS;
+                    }
                 }
                 break;
             }

tests/math.in

@@ -8,6 +8,7 @@ math '10 % 6'
 math -s0 '10 % 6'
 math '23 % 7'
 math --scale=6 '5 / 3 * 0.3'
+math --scale=max '5 / 3'
 math "7^2"
 math -1 + 1
 math '-2 * -2'

tests/math.out

@@ -10,6 +10,7 @@
 4
 2
 0.5
+1.666666666666667
 49
 0
 4