add pure go regex implementation for non-cgo build

Author: makiuchi-d

enginetest/queries/regex_queries.go

@@ -23,8 +23,7 @@ package queries
 import (
 	"gopkg.in/src-d/go-errors.v1"
 
-	regex "github.com/dolthub/go-icu-regex"
-
+	"github.com/dolthub/go-mysql-server/internal/regex"
 	"github.com/dolthub/go-mysql-server/sql"
 )
 

internal/regex/regex_cgo.go

@@ -0,0 +1,31 @@
+//go:build cgo
+
+package regex
+
+import regex "github.com/dolthub/go-icu-regex"
+
+type Regex = regex.Regex
+
+var (
+	ErrRegexNotYetSet = regex.ErrRegexNotYetSet
+	ErrMatchNotYetSet = regex.ErrMatchNotYetSet
+	ErrInvalidRegex   = regex.ErrInvalidRegex
+)
+
+type RegexFlags = regex.RegexFlags
+
+const (
+	RegexFlags_None                     = regex.RegexFlags_None
+	RegexFlags_Case_Insensitive         = regex.RegexFlags_Case_Insensitive
+	RegexFlags_Comments                 = regex.RegexFlags_Comments
+	RegexFlags_Dot_All                  = regex.RegexFlags_Dot_All
+	RegexFlags_Literal                  = regex.RegexFlags_Literal
+	RegexFlags_Multiline                = regex.RegexFlags_Multiline
+	RegexFlags_Unix_Lines               = regex.RegexFlags_Unix_Lines
+	RegexFlags_Unicode_Word             = regex.RegexFlags_Unicode_Word
+	RegexFlags_Error_On_Unknown_Escapes = regex.RegexFlags_Error_On_Unknown_Escapes
+)
+
+func CreateRegex(stringBufferInBytes uint32) Regex {
+	return regex.CreateRegex(stringBufferInBytes)
+}

internal/regex/regex_pure.go

@@ -0,0 +1,203 @@
+//go:build !cgo
+
+package regex
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+
+	"gopkg.in/src-d/go-errors.v1"
+)
+
+type Regex interface {
+	SetRegexString(ctx context.Context, regexStr string, flags RegexFlags) error
+	SetMatchString(ctx context.Context, matchStr string) error
+	IndexOf(ctx context.Context, start int, occurrence int, endIndex bool) (int, error)
+	Matches(ctx context.Context, start int, occurrence int) (bool, error)
+	Replace(ctx context.Context, replacementStr string, position int, occurrence int) (string, error)
+	Substring(ctx context.Context, start int, occurrence int) (string, bool, error)
+	Close() error
+}
+
+var (
+	ErrRegexNotYetSet = errors.NewKind("SetRegexString must be called before any other function")
+	ErrMatchNotYetSet = errors.NewKind("SetMatchString must be called as there is nothing to match against")
+	ErrInvalidRegex   = errors.NewKind("the given regular expression is invalid")
+)
+
+type RegexFlags uint32
+
+const (
+	RegexFlags_None                     RegexFlags = 0
+	RegexFlags_Case_Insensitive         RegexFlags = 2
+	RegexFlags_Comments                 RegexFlags = 4
+	RegexFlags_Dot_All                  RegexFlags = 32
+	RegexFlags_Literal                  RegexFlags = 16
+	RegexFlags_Multiline                RegexFlags = 8
+	RegexFlags_Unix_Lines               RegexFlags = 1
+	RegexFlags_Unicode_Word             RegexFlags = 256
+	RegexFlags_Error_On_Unknown_Escapes RegexFlags = 512
+)
+
+func CreateRegex(stringBufferInBytes uint32) Regex {
+	return &privateRegex{}
+}
+
+type privateRegex struct {
+	re   *regexp.Regexp
+	str  string
+	sset bool
+
+	done  bool
+	start int
+	locs  [][]int
+}
+
+var _ Regex = (*privateRegex)(nil)
+
+func (pr *privateRegex) SetRegexString(ctx context.Context, regexStr string, flags RegexFlags) (err error) {
+	// i : RegexFlags_Case_Insensitive
+	// m : RegexFlags_Multiline
+	// s : RegexFlags_Dot_All
+	//     RegexFlags_Unix_Lines
+	var flg = "(?"
+	if flags&RegexFlags_Case_Insensitive != 0 {
+		flg += "i"
+	}
+	if flags&RegexFlags_Multiline != 0 {
+		flg += "m"
+	}
+	if flags&RegexFlags_Dot_All != 0 {
+		flg += "s"
+	}
+	if len(flg) > 2 {
+		flg += ")"
+	} else {
+		flg = ""
+	}
+
+	pr.done = false
+	pr.sset = false
+	pr.re, err = regexp.Compile(flg + regexStr)
+	if err != nil {
+		return ErrInvalidRegex.New()
+	}
+	return nil
+}
+
+func (pr *privateRegex) SetMatchString(ctx context.Context, matchStr string) (err error) {
+	if pr.re == nil {
+		return ErrRegexNotYetSet.New()
+	}
+	pr.done = false
+	pr.str = matchStr
+	pr.sset = true
+	return nil
+}
+
+func (pr *privateRegex) do(start int) error {
+	if start < 1 {
+		start = 1
+	}
+	if !pr.done || pr.start != start {
+		if pr.re == nil {
+			return ErrRegexNotYetSet.New()
+		}
+		if !pr.sset {
+			return ErrMatchNotYetSet.New()
+		}
+		pr.locs = pr.re.FindAllStringIndex(pr.str[start-1:], -1)
+		pr.start = start
+		pr.done = true
+	}
+	return nil
+}
+
+func (pr *privateRegex) location(occurrence int) []int {
+	occurrence--
+	if occurrence < 0 {
+		occurrence = 0
+	}
+	if len(pr.locs) < occurrence+1 {
+		return nil
+	}
+	return pr.locs[occurrence]
+}
+
+func (pr *privateRegex) IndexOf(ctx context.Context, start int, occurrence int, endIndex bool) (int, error) {
+	err := pr.do(start)
+	if err != nil {
+		return 0, err
+	}
+	loc := pr.location(occurrence)
+	if loc == nil {
+		return 0, nil
+	}
+	pos := loc[0]
+	if endIndex {
+		pos = loc[1]
+	}
+	return pos + pr.start, nil
+}
+
+func (pr *privateRegex) Matches(ctx context.Context, start int, occurrence int) (bool, error) {
+	err := pr.do(start + 1) // start+1: issue #10 (https://github.com/dolthub/go-icu-regex/issues/10)
+	if err != nil {
+		return false, err
+	}
+	loc := pr.location(occurrence)
+	return loc != nil, nil
+}
+
+func (pr *privateRegex) Replace(ctx context.Context, replacement string, start int, occurrence int) (string, error) {
+	err := pr.do(start)
+	if err != nil {
+		return "", err
+	}
+
+	var locs [][]int
+	if occurrence == 0 {
+		locs = pr.locs
+	} else {
+		loc := pr.location(occurrence)
+		if loc != nil {
+			locs = [][]int{loc}
+		}
+	}
+	offs := pr.start - 1
+	pos := offs
+	ret := []byte(pr.str[:pos])
+	for _, loc := range locs {
+		ret = fmt.Appendf(ret, "%s%s", pr.str[pos:loc[0]+offs], replacement)
+		pos = loc[1] + offs
+	}
+	ret = fmt.Append(ret, pr.str[pos:])
+	return string(ret), nil
+
+	loc := pr.location(occurrence)
+	if loc == nil {
+		return pr.str, nil
+	}
+	return pr.str[:loc[0]+pr.start-1] + replacement + pr.str[loc[1]+pr.start-1:], nil
+}
+
+func (pr *privateRegex) Substring(ctx context.Context, start int, occurrence int) (string, bool, error) {
+	err := pr.do(start)
+	if err != nil {
+		return "", false, err
+	}
+	loc := pr.location(occurrence)
+	if loc == nil {
+		return "", false, nil
+	}
+	return pr.str[loc[0]+pr.start-1 : loc[1]+pr.start-1], true, nil
+}
+
+func (pr *privateRegex) Close() (err error) {
+	pr.re = nil
+	pr.str = ""
+	pr.done = false
+	pr.locs = nil
+	return nil
+}