Enables mssql support (#383)

* Enables mssql support

Port of dlobs work in gogs.
Enables options in index.js
Enables MSSQL as a database option in go.
Sets ID to 0 on initial migration. Required for
MSSQL insert statements.

Signed-off-by: Beau Trepp <beautrepp@gmail.com>

* Vendors in denisenkom/go-mssqldb

Includes golang.org/x/crypto/md4
as this is required by go-msssqldb

Signed-off-by: Beau Trepp <beautrepp@gmail.com>

vendor/github.com/denisenkom/go-mssqldb/parser.go

@@ -0,0 +1,227 @@
+package mssql
+
+import (
+	"bytes"
+	"io"
+	"strconv"
+)
+
+type parser struct {
+	r          *bytes.Reader
+	w          bytes.Buffer
+	paramCount int
+	paramMax   int
+}
+
+func (p *parser) next() (rune, bool) {
+	ch, _, err := p.r.ReadRune()
+	if err != nil {
+		if err != io.EOF {
+			panic(err)
+		}
+		return 0, false
+	}
+	return ch, true
+}
+
+func (p *parser) unread() {
+	err := p.r.UnreadRune()
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (p *parser) write(ch rune) {
+	p.w.WriteRune(ch)
+}
+
+type stateFunc func(*parser) stateFunc
+
+func parseParams(query string) (string, int) {
+	p := &parser{
+		r: bytes.NewReader([]byte(query)),
+	}
+	state := parseNormal
+	for state != nil {
+		state = state(p)
+	}
+	return p.w.String(), p.paramMax
+}
+
+func parseNormal(p *parser) stateFunc {
+	for {
+		ch, ok := p.next()
+		if !ok {
+			return nil
+		}
+		if ch == '?' {
+			return parseParameter
+		} else if ch == '$' || ch == ':' {
+			ch2, ok := p.next()
+			if !ok {
+				p.write(ch)
+				return nil
+			}
+			p.unread()
+			if ch2 >= '0' && ch2 <= '9' {
+				return parseParameter
+			}
+		}
+		p.write(ch)
+		switch ch {
+		case '\'':
+			return parseQuote
+		case '"':
+			return parseDoubleQuote
+		case '[':
+			return parseBracket
+		case '-':
+			return parseLineComment
+		case '/':
+			return parseComment
+		}
+	}
+}
+
+func parseParameter(p *parser) stateFunc {
+	var paramN int
+	var ok bool
+	for {
+		var ch rune
+		ch, ok = p.next()
+		if ok && ch >= '0' && ch <= '9' {
+			paramN = paramN*10 + int(ch-'0')
+		} else {
+			break
+		}
+	}
+	if ok {
+		p.unread()
+	}
+	if paramN == 0 {
+		p.paramCount++
+		paramN = p.paramCount
+	}
+	if paramN > p.paramMax {
+		p.paramMax = paramN
+	}
+	p.w.WriteString("@p")
+	p.w.WriteString(strconv.Itoa(paramN))
+	if !ok {
+		return nil
+	}
+	return parseNormal
+}
+
+func parseQuote(p *parser) stateFunc {
+	for {
+		ch, ok := p.next()
+		if !ok {
+			return nil
+		}
+		p.write(ch)
+		if ch == '\'' {
+			return parseNormal
+		}
+	}
+}
+
+func parseDoubleQuote(p *parser) stateFunc {
+	for {
+		ch, ok := p.next()
+		if !ok {
+			return nil
+		}
+		p.write(ch)
+		if ch == '"' {
+			return parseNormal
+		}
+	}
+}
+
+func parseBracket(p *parser) stateFunc {
+	for {
+		ch, ok := p.next()
+		if !ok {
+			return nil
+		}
+		p.write(ch)
+		if ch == ']' {
+			ch, ok = p.next()
+			if !ok {
+				return nil
+			}
+			if ch != ']' {
+				p.unread()
+				return parseNormal
+			}
+			p.write(ch)
+		}
+	}
+}
+
+func parseLineComment(p *parser) stateFunc {
+	ch, ok := p.next()
+	if !ok {
+		return nil
+	}
+	if ch != '-' {
+		p.unread()
+		return parseNormal
+	}
+	p.write(ch)
+	for {
+		ch, ok = p.next()
+		if !ok {
+			return nil
+		}
+		p.write(ch)
+		if ch == '\n' {
+			return parseNormal
+		}
+	}
+}
+
+func parseComment(p *parser) stateFunc {
+	var nested int
+	ch, ok := p.next()
+	if !ok {
+		return nil
+	}
+	if ch != '*' {
+		p.unread()
+		return parseNormal
+	}
+	p.write(ch)
+	for {
+		ch, ok = p.next()
+		if !ok {
+			return nil
+		}
+		p.write(ch)
+		for ch == '*' {
+			ch, ok = p.next()
+			if !ok {
+				return nil
+			}
+			p.write(ch)
+			if ch == '/' {
+				if nested == 0 {
+					return parseNormal
+				} else {
+					nested--
+				}
+			}
+		}
+		for ch == '/' {
+			ch, ok = p.next()
+			if !ok {
+				return nil
+			}
+			p.write(ch)
+			if ch == '*' {
+				nested++
+			}
+		}
+	}
+}