util_match.go

package main

// Most of the code in this file is extracted from golang's src/testing/match.go.
//
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

import (
	"fmt"
	"regexp"
	"strings"
	"unicode"
)

type filterMatch interface {
	// matches checks the name against the receiver's pattern strings using the
	// given match function.
	matches(name []string, matchString func(pat, str string) (bool, error)) (ok, partial bool)

	// verify checks that the receiver's pattern strings are valid filters by
	// calling the given match function.
	verify(name string, matchString func(pat, str string) (bool, error)) error
}

// simpleMatch matches a test name if all of the pattern strings match in
// sequence.
type simpleMatch []string

// alternationMatch matches a test name if one of the alternations match.
type alternationMatch []filterMatch

func (m simpleMatch) matches(name []string, matchString func(pat, str string) (bool, error)) (ok, partial bool) {
	for i, s := range name {
		if i >= len(m) {
			break
		}
		if ok, _ := matchString(m[i], s); !ok {
			return false, false
		}
	}
	return true, len(name) < len(m)
}

func (m simpleMatch) verify(name string, matchString func(pat, str string) (bool, error)) error {
	for i, s := range m {
		m[i] = rewrite(s)
	}
	// Verify filters before doing any processing.
	for i, s := range m {
		if _, err := matchString(s, "non-empty"); err != nil {
			return fmt.Errorf("element %d of %s (%q): %w", i, name, s, err)
		}
	}
	return nil
}

func (m alternationMatch) matches(name []string, matchString func(pat, str string) (bool, error)) (ok, partial bool) {
	for _, m := range m {
		if ok, partial = m.matches(name, matchString); ok {
			return ok, partial
		}
	}
	return false, false
}

func (m alternationMatch) verify(name string, matchString func(pat, str string) (bool, error)) error {
	for i, m := range m {
		if err := m.verify(name, matchString); err != nil {
			return fmt.Errorf("alternation %d of %w", i, err)
		}
	}
	return nil
}

func splitRegexp(s string) filterMatch {
	a := make(simpleMatch, 0, strings.Count(s, "/"))
	b := make(alternationMatch, 0, strings.Count(s, "|"))
	cs := 0
	cp := 0
	for i := 0; i < len(s); {
		switch s[i] {
		case '[':
			cs++
		case ']':
			if cs--; cs < 0 { // An unmatched ']' is legal.
				cs = 0
			}
		case '(':
			if cs == 0 {
				cp++
			}
		case ')':
			if cs == 0 {
				cp--
			}
		case '\\':
			i++
		case '/':
			if cs == 0 && cp == 0 {
				a = append(a, s[:i])
				s = s[i+1:]
				i = 0
				continue
			}
		case '|':
			if cs == 0 && cp == 0 {
				a = append(a, s[:i])
				s = s[i+1:]
				i = 0
				b = append(b, a)
				a = make(simpleMatch, 0, len(a))
				continue
			}
		}
		i++
	}

	a = append(a, s)
	if len(b) == 0 {
		return a
	}
	return append(b, a)
}

// rewrite rewrites a subname to having only printable characters and no white
// space.
func rewrite(s string) string {
	b := []byte{}
	for _, r := range s {
		switch {
		case isSpace(r):
			b = append(b, '_')
		case !unicode.IsPrint(r):
			s := simpleQuoteRune(r)
			b = append(b, s[1:len(s)-1]...)
		default:
			b = append(b, string(r)...)
		}
	}
	return string(b)
}

// simpleQuoteRune does not follow the original strconv.QuoteRune.
func simpleQuoteRune(r rune) string {
	return "."
}

func isSpace(r rune) bool {
	if r < 0x2000 {
		switch r {
		// Note: not the same as Unicode Z class.
		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0, 0x1680:
			return true
		}
	} else {
		if r <= 0x200a {
			return true
		}
		switch r {
		case 0x2028, 0x2029, 0x202f, 0x205f, 0x3000:
			return true
		}
	}
	return false
}

var (
	matchPat string
	matchRe  *regexp.Regexp
)

// based on testing/internal/testdeps.TestDeps.MatchString.
func matchString(pat, str string) (result bool, err error) {
	if matchRe == nil || matchPat != pat {
		matchPat = pat
		matchRe, err = regexp.Compile(matchPat)
		if err != nil {
			return
		}
	}
	return matchRe.MatchString(str), nil
}