Switch Unicode Escaping to a VSCode-like system (#19990)

This PR rewrites the invisible unicode detection algorithm to more
closely match that of the Monaco editor on the system. It provides a
technique for detecting ambiguous characters and relaxes the detection
of combining marks.

Control characters are in addition detected as invisible in this
implementation whereas they are not on monaco but this is related to
font issues.

Close #19913

Signed-off-by: Andrew Thornton <art27@cantab.net>

1 files changed, 111 insertions, 0 deletions

diff --git a/modules/charset/invisible/generate.go b/modules/charset/invisible/generate.go
new file mode 100644
index 0000000000..230ff0b832
--- /dev/null
+++ b/modules/charset/invisible/generate.go
@@ -0,0 +1,111 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/format"
+	"os"
+	"text/template"
+
+	"golang.org/x/text/unicode/rangetable"
+)
+
+// InvisibleRunes these are runes that vscode has assigned to be invisible
+// See https://github.com/hediet/vscode-unicode-data
+var InvisibleRunes = []rune{
+	9, 10, 11, 12, 13, 32, 127, 160, 173, 847, 1564, 4447, 4448, 6068, 6069, 6155, 6156, 6157, 6158, 7355, 7356, 8192, 8193, 8194, 8195, 8196, 8197, 8198, 8199, 8200, 8201, 8202, 8203, 8204, 8205, 8206, 8207, 8234, 8235, 8236, 8237, 8238, 8239, 8287, 8288, 8289, 8290, 8291, 8292, 8293, 8294, 8295, 8296, 8297, 8298, 8299, 8300, 8301, 8302, 8303, 10240, 12288, 12644, 65024, 65025, 65026, 65027, 65028, 65029, 65030, 65031, 65032, 65033, 65034, 65035, 65036, 65037, 65038, 65039, 65279, 65440, 65520, 65521, 65522, 65523, 65524, 65525, 65526, 65527, 65528, 65532, 78844, 119155, 119156, 119157, 119158, 119159, 119160, 119161, 119162, 917504, 917505, 917506, 917507, 917508, 917509, 917510, 917511, 917512, 917513, 917514, 917515, 917516, 917517, 917518, 917519, 917520, 917521, 917522, 917523, 917524, 917525, 917526, 917527, 917528, 917529, 917530, 917531, 917532, 917533, 917534, 917535, 917536, 917537, 917538, 917539, 917540, 917541, 917542, 917543, 917544, 917545, 917546, 917547, 917548, 917549, 917550, 917551, 917552, 917553, 917554, 917555, 917556, 917557, 917558, 917559, 917560, 917561, 917562, 917563, 917564, 917565, 917566, 917567, 917568, 917569, 917570, 917571, 917572, 917573, 917574, 917575, 917576, 917577, 917578, 917579, 917580, 917581, 917582, 917583, 917584, 917585, 917586, 917587, 917588, 917589, 917590, 917591, 917592, 917593, 917594, 917595, 917596, 917597, 917598, 917599, 917600, 917601, 917602, 917603, 917604, 917605, 917606, 917607, 917608, 917609, 917610, 917611, 917612, 917613, 917614, 917615, 917616, 917617, 917618, 917619, 917620, 917621, 917622, 917623, 917624, 917625, 917626, 917627, 917628, 917629, 917630, 917631, 917760, 917761, 917762, 917763, 917764, 917765, 917766, 917767, 917768, 917769, 917770, 917771, 917772, 917773, 917774, 917775, 917776, 917777, 917778, 917779, 917780, 917781, 917782, 917783, 917784, 917785, 917786, 917787, 917788, 917789, 917790, 917791, 917792, 917793, 917794, 917795, 917796, 917797, 917798, 917799, 917800, 917801, 917802, 917803, 917804, 917805, 917806, 917807, 917808, 917809, 917810, 917811, 917812, 917813, 917814, 917815, 917816, 917817, 917818, 917819, 917820, 917821, 917822, 917823, 917824, 917825, 917826, 917827, 917828, 917829, 917830, 917831, 917832, 917833, 917834, 917835, 917836, 917837, 917838, 917839, 917840, 917841, 917842, 917843, 917844, 917845, 917846, 917847, 917848, 917849, 917850, 917851, 917852, 917853, 917854, 917855, 917856, 917857, 917858, 917859, 917860, 917861, 917862, 917863, 917864, 917865, 917866, 917867, 917868, 917869, 917870, 917871, 917872, 917873, 917874, 917875, 917876, 917877, 917878, 917879, 917880, 917881, 917882, 917883, 917884, 917885, 917886, 917887, 917888, 917889, 917890, 917891, 917892, 917893, 917894, 917895, 917896, 917897, 917898, 917899, 917900, 917901, 917902, 917903, 917904, 917905, 917906, 917907, 917908, 917909, 917910, 917911, 917912, 917913, 917914, 917915, 917916, 917917, 917918, 917919, 917920, 917921, 917922, 917923, 917924, 917925, 917926, 917927, 917928, 917929, 917930, 917931, 917932, 917933, 917934, 917935, 917936, 917937, 917938, 917939, 917940, 917941, 917942, 917943, 917944, 917945, 917946, 917947, 917948, 917949, 917950, 917951, 917952, 917953, 917954, 917955, 917956, 917957, 917958, 917959, 917960, 917961, 917962, 917963, 917964, 917965, 917966, 917967, 917968, 917969, 917970, 917971, 917972, 917973, 917974, 917975, 917976, 917977, 917978, 917979, 917980, 917981, 917982, 917983, 917984, 917985, 917986, 917987, 917988, 917989, 917990, 917991, 917992, 917993, 917994, 917995, 917996, 917997, 917998, 917999,
+}
+
+var verbose bool
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, `%s: Generate InvisibleRunesRange
+
+Usage: %[1]s [-v] [-o output.go]
+`, os.Args[0])
+		flag.PrintDefaults()
+	}
+
+	output := ""
+	flag.BoolVar(&verbose, "v", false, "verbose output")
+	flag.StringVar(&output, "o", "invisible_gen.go", "file to output to")
+	flag.Parse()
+
+	// First we filter the runes to remove
+	// <space><tab><newline>
+	filtered := make([]rune, 0, len(InvisibleRunes))
+	for _, r := range InvisibleRunes {
+		if r == ' ' || r == '\t' || r == '\n' {
+			continue
+		}
+		filtered = append(filtered, r)
+	}
+
+	table := rangetable.New(filtered...)
+	if err := runTemplate(generatorTemplate, output, table); err != nil {
+		fatalf("Unable to run template: %v", err)
+	}
+}
+
+func runTemplate(t *template.Template, filename string, data interface{}) error {
+	buf := bytes.NewBuffer(nil)
+	if err := t.Execute(buf, data); err != nil {
+		return fmt.Errorf("unable to execute template: %w", err)
+	}
+	bs, err := format.Source(buf.Bytes())
+	if err != nil {
+		verbosef("Bad source:\n%s", buf.String())
+		return fmt.Errorf("unable to format source: %w", err)
+	}
+	file, err := os.Create(filename)
+	if err != nil {
+		return fmt.Errorf("failed to create file %s because %w", filename, err)
+	}
+	defer file.Close()
+	_, err = file.Write(bs)
+	if err != nil {
+		return fmt.Errorf("unable to write generated source: %w", err)
+	}
+	return nil
+}
+
+var generatorTemplate = template.Must(template.New("invisibleTemplate").Parse(`// This file is generated by modules/charset/invisible/generate.go DO NOT EDIT
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package charset
+
+import "unicode"
+
+var InvisibleRanges = &unicode.RangeTable{
+	R16: []unicode.Range16{
+{{range .R16 }}		{Lo:{{.Lo}}, Hi:{{.Hi}}, Stride: {{.Stride}}},
+{{end}}	},
+	R32: []unicode.Range32{
+{{range .R32}}		{Lo:{{.Lo}}, Hi:{{.Hi}}, Stride: {{.Stride}}},
+{{end}}	},
+	LatinOffset: {{.LatinOffset}},
+}
+`))
+
+func logf(format string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, format+"\n", args...)
+}
+
+func verbosef(format string, args ...interface{}) {
+	if verbose {
+		logf(format, args...)
+	}
+}
+
+func fatalf(format string, args ...interface{}) {
+	logf("fatal: "+format+"\n", args...)
+	os.Exit(1)
+}