Server-side syntax highlighting for all code (#12047)

* Server-side syntax hilighting for all code

This PR does a few things:

* Remove all traces of highlight.js
* Use chroma library to provide fast syntax hilighting directly on the server
* Provide syntax hilighting for diffs
* Re-style both unified and split diffs views
* Add custom syntax hilighting styling for both regular and arc-green

Fixes #7729
Fixes #10157
Fixes #11825
Fixes #7728
Fixes #3872
Fixes #3682

And perhaps gets closer to #9553

* fix line marker

* fix repo search

* Fix single line select

* properly load settings

* npm uninstall highlight.js

* review suggestion

* code review

* forgot to call function

* fix test

* Apply suggestions from code review

suggestions from @silverwind thanks

Co-authored-by: silverwind <me@silverwind.io>

* code review

* copy/paste error

* Use const for highlight size limit

* Update web_src/less/_repository.less

Co-authored-by: Lauris BH <lauris@nix.lv>

* update size limit to 1MB and other styling tweaks

* fix highlighting for certain diff sections

* fix test

* add worker back as suggested

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

vendor/github.com/danwakefield/fnmatch/.gitignore

@@ -0,0 +1,24 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof

vendor/github.com/danwakefield/fnmatch/LICENSE

@@ -0,0 +1,23 @@
+Copyright (c) 2016, Daniel Wakefield
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/danwakefield/fnmatch/README.md

@@ -0,0 +1,4 @@
+# fnmatch
+Updated clone of kballards golang fnmatch gist (https://gist.github.com/kballard/272720)
+
+

vendor/github.com/danwakefield/fnmatch/fnmatch.go

@@ -0,0 +1,219 @@
+// Provide string-matching based on fnmatch.3
+package fnmatch
+
+// There are a few issues that I believe to be bugs, but this implementation is
+// based as closely as possible on BSD fnmatch. These bugs are present in the
+// source of BSD fnmatch, and so are replicated here. The issues are as follows:
+//
+// * FNM_PERIOD is no longer observed after the first * in a pattern
+//   This only applies to matches done with FNM_PATHNAME as well
+// * FNM_PERIOD doesn't apply to ranges. According to the documentation,
+//   a period must be matched explicitly, but a range will match it too
+
+import (
+	"unicode"
+	"unicode/utf8"
+)
+
+const (
+	FNM_NOESCAPE = (1 << iota)
+	FNM_PATHNAME
+	FNM_PERIOD
+
+	FNM_LEADING_DIR
+	FNM_CASEFOLD
+
+	FNM_IGNORECASE = FNM_CASEFOLD
+	FNM_FILE_NAME  = FNM_PATHNAME
+)
+
+func unpackRune(str *string) rune {
+	rune, size := utf8.DecodeRuneInString(*str)
+	*str = (*str)[size:]
+	return rune
+}
+
+// Matches the pattern against the string, with the given flags,
+// and returns true if the match is successful.
+// This function should match fnmatch.3 as closely as possible.
+func Match(pattern, s string, flags int) bool {
+	// The implementation for this function was patterned after the BSD fnmatch.c
+	// source found at http://src.gnu-darwin.org/src/contrib/csup/fnmatch.c.html
+	noescape := (flags&FNM_NOESCAPE != 0)
+	pathname := (flags&FNM_PATHNAME != 0)
+	period := (flags&FNM_PERIOD != 0)
+	leadingdir := (flags&FNM_LEADING_DIR != 0)
+	casefold := (flags&FNM_CASEFOLD != 0)
+	// the following is some bookkeeping that the original fnmatch.c implementation did not do
+	// We are forced to do this because we're not keeping indexes into C strings but rather
+	// processing utf8-encoded strings. Use a custom unpacker to maintain our state for us
+	sAtStart := true
+	sLastAtStart := true
+	sLastSlash := false
+	sLastUnpacked := rune(0)
+	unpackS := func() rune {
+		sLastSlash = (sLastUnpacked == '/')
+		sLastUnpacked = unpackRune(&s)
+		sLastAtStart = sAtStart
+		sAtStart = false
+		return sLastUnpacked
+	}
+	for len(pattern) > 0 {
+		c := unpackRune(&pattern)
+		switch c {
+		case '?':
+			if len(s) == 0 {
+				return false
+			}
+			sc := unpackS()
+			if pathname && sc == '/' {
+				return false
+			}
+			if period && sc == '.' && (sLastAtStart || (pathname && sLastSlash)) {
+				return false
+			}
+		case '*':
+			// collapse multiple *'s
+			// don't use unpackRune here, the only char we care to detect is ASCII
+			for len(pattern) > 0 && pattern[0] == '*' {
+				pattern = pattern[1:]
+			}
+			if period && s[0] == '.' && (sAtStart || (pathname && sLastUnpacked == '/')) {
+				return false
+			}
+			// optimize for patterns with * at end or before /
+			if len(pattern) == 0 {
+				if pathname {
+					return leadingdir || (strchr(s, '/') == -1)
+				} else {
+					return true
+				}
+				return !(pathname && strchr(s, '/') >= 0)
+			} else if pathname && pattern[0] == '/' {
+				offset := strchr(s, '/')
+				if offset == -1 {
+					return false
+				} else {
+					// we already know our pattern and string have a /, skip past it
+					s = s[offset:] // use unpackS here to maintain our bookkeeping state
+					unpackS()
+					pattern = pattern[1:] // we know / is one byte long
+					break
+				}
+			}
+			// general case, recurse
+			for test := s; len(test) > 0; unpackRune(&test) {
+				// I believe the (flags &^ FNM_PERIOD) is a bug when FNM_PATHNAME is specified
+				// but this follows exactly from how fnmatch.c implements it
+				if Match(pattern, test, (flags &^ FNM_PERIOD)) {
+					return true
+				} else if pathname && test[0] == '/' {
+					break
+				}
+			}
+			return false
+		case '[':
+			if len(s) == 0 {
+				return false
+			}
+			if pathname && s[0] == '/' {
+				return false
+			}
+			sc := unpackS()
+			if !rangematch(&pattern, sc, flags) {
+				return false
+			}
+		case '\\':
+			if !noescape {
+				if len(pattern) > 0 {
+					c = unpackRune(&pattern)
+				}
+			}
+			fallthrough
+		default:
+			if len(s) == 0 {
+				return false
+			}
+			sc := unpackS()
+			switch {
+			case sc == c:
+			case casefold && unicode.ToLower(sc) == unicode.ToLower(c):
+			default:
+				return false
+			}
+		}
+	}
+	return len(s) == 0 || (leadingdir && s[0] == '/')
+}
+
+func rangematch(pattern *string, test rune, flags int) bool {
+	if len(*pattern) == 0 {
+		return false
+	}
+	casefold := (flags&FNM_CASEFOLD != 0)
+	noescape := (flags&FNM_NOESCAPE != 0)
+	if casefold {
+		test = unicode.ToLower(test)
+	}
+	var negate, matched bool
+	if (*pattern)[0] == '^' || (*pattern)[0] == '!' {
+		negate = true
+		(*pattern) = (*pattern)[1:]
+	}
+	for !matched && len(*pattern) > 1 && (*pattern)[0] != ']' {
+		c := unpackRune(pattern)
+		if !noescape && c == '\\' {
+			if len(*pattern) > 1 {
+				c = unpackRune(pattern)
+			} else {
+				return false
+			}
+		}
+		if casefold {
+			c = unicode.ToLower(c)
+		}
+		if (*pattern)[0] == '-' && len(*pattern) > 1 && (*pattern)[1] != ']' {
+			unpackRune(pattern) // skip the -
+			c2 := unpackRune(pattern)
+			if !noescape && c2 == '\\' {
+				if len(*pattern) > 0 {
+					c2 = unpackRune(pattern)
+				} else {
+					return false
+				}
+			}
+			if casefold {
+				c2 = unicode.ToLower(c2)
+			}
+			// this really should be more intelligent, but it looks like
+			// fnmatch.c does simple int comparisons, therefore we will as well
+			if c <= test && test <= c2 {
+				matched = true
+			}
+		} else if c == test {
+			matched = true
+		}
+	}
+	// skip past the rest of the pattern
+	ok := false
+	for !ok && len(*pattern) > 0 {
+		c := unpackRune(pattern)
+		if c == '\\' && len(*pattern) > 0 {
+			unpackRune(pattern)
+		} else if c == ']' {
+			ok = true
+		}
+	}
+	return ok && matched != negate
+}
+
+// define strchr because strings.Index() seems a bit overkill
+// returns the index of c in s, or -1 if there is no match
+func strchr(s string, c rune) int {
+	for i, sc := range s {
+		if sc == c {
+			return i
+		}
+	}
+	return -1
+}