initial commit

.github/workflows/test.yml

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+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.14.x, 1.15.x]
+        os: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Test
+      run: go test ./...

.gitignore

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+# Ignore everything
+*
+# Whitelist subdirectories
+!*/
+# Whitelist the following files and extensions
+!*.yml
+!*.gz
+!.gitignore
+!go.mod
+!go.sum
+!*.md
+!*.go

LICENSE.md

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+# MIT License
+
+Copyright (c) 2020 Akhil Indurti
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# xid
+
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/smasher164/xid)](https://pkg.go.dev/github.com/smasher164/xid)
+![Test](https://github.com/smasher164/xid/workflows/Test/badge.svg)
+
+Package xid implements validation functions for unicode identifiers,
+as defined in UAX#31: https://unicode.org/reports/tr31/.
+The syntax for an identifier is:
+
+    <identifier> := <xid_start> <xid_continue>*
+
+where `<xid_start>` and `<xid_continue>` derive from `<id_start>` and
+`<id_continue>`, respectively, and check their NFKC normalized forms.

go.mod

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+module github.com/smasher164/xid
+
+go 1.15
+
+require golang.org/x/text v0.3.3

go.sum

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+golang.org/x/text v0.3.3 h1:cokOdA+Jmi5PJGXLlLllQSgYigAEfHXJAERHVMaCc2k=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

unicodeTestVersion_114.go

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+// +build go1.14
+
+package xid
+
+const unicodeTestVersion = "12.1.0"

xid.go

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+// Package xid implements validation functions for unicode identifiers,
+// as defined in UAX#31: https://unicode.org/reports/tr31/.
+// The syntax for an identifier is:
+//
+//     <identifier> := <xid_start> <xid_continue>*
+//
+// where <xid_start> and <xid_continue> derive from <id_start> and
+// <id_continue>, respectively, and check their NFKC normalized forms.
+package xid
+
+import (
+	"unicode"
+
+	"golang.org/x/text/unicode/norm"
+)
+
+type set func(rune) bool
+
+func (a set) add(rt *unicode.RangeTable) set {
+	b := in(rt)
+	return func(r rune) bool { return a(r) || b(r) }
+}
+
+func (a set) sub(rt *unicode.RangeTable) set {
+	b := in(rt)
+	return func(r rune) bool { return a(r) && !b(r) }
+}
+
+func in(rt *unicode.RangeTable) set {
+	return func(r rune) bool { return unicode.Is(rt, r) }
+}
+
+var id_start = set(unicode.IsLetter).
+	add(unicode.Nl).
+	add(unicode.Other_ID_Start).
+	sub(unicode.Pattern_Syntax).
+	sub(unicode.Pattern_White_Space)
+
+var id_continue = id_start.
+	add(unicode.Mn).
+	add(unicode.Mc).
+	add(unicode.Nd).
+	add(unicode.Pc).
+	add(unicode.Other_ID_Continue).
+	sub(unicode.Pattern_Syntax).
+	sub(unicode.Pattern_White_Space)
+
+// Start checks that the rune begins an identifier.
+func Start(r rune) bool {
+	// id_start(r) && NFKC(r) in "id_start xid_continue*"
+	if !id_start(r) {
+		return false
+	}
+	s := norm.NFKC.String(string(r))
+	if s == "" {
+		return false
+	}
+	for i, r := range s {
+		if i == 0 {
+			if !id_start(r) {
+				return false
+			}
+		} else {
+			if !Continue(r) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Continue checks that the rune continues an identifier.
+func Continue(r rune) bool {
+	// id_continue(r) && NFKC(r) in "id_continue*"
+	if !id_continue(r) {
+		return false
+	}
+	for _, r := range norm.NFKC.String(string(r)) {
+		if !id_continue(r) {
+			return false
+		}
+	}
+	return true
+}

xid_test.go

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+package xid
+
+import (
+	"bufio"
+	"compress/gzip"
+	"os"
+	"path/filepath"
+	"strconv"
+	"testing"
+	"unicode"
+)
+
+func readMatches(file string) ([]bool, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	rdr, err := gzip.NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+	defer rdr.Close()
+	scanner := bufio.NewScanner(rdr)
+	scanner.Split(bufio.ScanBytes)
+	var matches []bool
+	for scanner.Scan() {
+		b, err := strconv.ParseBool(scanner.Text())
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, b)
+	}
+	return matches, nil
+}
+
+func TestExhaustive(t *testing.T) {
+	cases := []struct {
+		class string
+		f     func(rune) bool
+	}{
+		{"xid_start", Start},
+		{"xid_continue", Continue},
+	}
+	for _, c := range cases {
+		t.Run(c.class, func(t *testing.T) {
+			matches, err := readMatches(filepath.Join("testdata", c.class+unicodeTestVersion+".txt.gz"))
+			if err != nil {
+				t.Fatal(err)
+			}
+			for r := rune(0); r <= unicode.MaxRune; r++ {
+				want := matches[r]
+				if got := c.f(r); got != want {
+					t.Fatalf("%s(%s)=%v, got=%v", c.class, strconv.QuoteRuneToASCII(r), want, got)
+				}
+			}
+		})
+	}
+}