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changeset_file.go
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changeset_file.go
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package pgit
import (
"strconv"
"strings"
"github.com/pkg/errors"
)
const (
changesetAnnotation = "-- change"
rollbackAnnotation = "-- rollback"
definitionAnnotation = "-- definition"
)
// changesetFile represents a file using the "changeset" method for describing
// database schema.
type changesetFile struct {
path string
changesets []changeset
}
// changeset contains the SQL for applying and rolling back a changeset
type changeset struct {
applySQL string
rollbackSQL string
}
func (c *changesetFile) getPath() string {
return c.path
}
func (c *changesetFile) getApplySQL(currentVersion string) (string, string, error) {
applySQL := ""
currentVersionNum, err := strconv.ParseUint(currentVersion, 10, 64)
if err != nil {
if currentVersion == "" {
currentVersionNum = 0
} else {
return "", "", errors.Wrap(err, "expected integer for currentVersion")
}
}
if currentVersionNum > uint64(len(c.changesets)) {
return "", "", errors.New("no changesets defined to reach specified version")
}
if currentVersionNum == uint64(len(c.changesets)) {
return "", currentVersion, nil
}
for i := currentVersionNum; i < uint64(len(c.changesets)); i++ {
applySQL += c.changesets[i].applySQL + "\n"
}
return applySQL, strconv.FormatInt(int64(len(c.changesets)), 10), nil
}
func (c *changesetFile) getRollbackSQL(currentVersion string) (string, string, error) {
currentVersionNum, err := strconv.ParseUint(currentVersion, 10, 64)
if err != nil {
if currentVersion == "" {
return "", "0", nil
}
return "", "", errors.Wrap(err, "expected integer for currentVersion")
}
if currentVersionNum == 0 {
return "", "0", nil
}
return c.changesets[currentVersionNum-1].rollbackSQL, strconv.FormatUint(currentVersionNum-1, 10), nil
}
// readFromFile populates the changeset
func (c *changesetFile) parse(fileContent []byte) error {
sep := "\r\n"
lines := strings.Split(string(fileContent), sep)
if len(lines) == 1 {
sep = "\n"
lines = strings.Split(string(fileContent), sep)
}
if len(lines) < 1 {
return errors.New("empty file")
}
captureRollback := func(i int) (int, string, error) {
r := ""
for j := i; j < len(lines); j++ {
if lines[j] == rollbackAnnotation {
return j, r, errors.Errorf("unexpected rollback statement (line %v)", j+1)
} else if lines[j] != changesetAnnotation {
r += lines[j] + "\n"
} else {
return j, r, nil
}
}
return len(lines), r, nil
}
captureChangeset := func(i int) (int, *changeset, error) {
c := &changeset{}
j := i
for ; j < len(lines); j++ {
if lines[j] == changesetAnnotation {
return 0, nil, errors.Errorf("unexpected changeset statement (line %v", j+1)
} else if lines[j] != rollbackAnnotation {
c.applySQL += lines[j] + "\n"
} else {
j, rollback, err := captureRollback(j + 1)
if err != nil {
return 0, nil, err
}
c.rollbackSQL = rollback
return j - 1, c, nil
}
}
if c.rollbackSQL == "" {
return 0, nil, errors.Errorf("missing rollback statement (line %v)", j)
}
return len(lines), c, nil
}
for i := 0; i < len(lines); i++ {
if lines[i] == changesetAnnotation {
newIndex, changeset, err := captureChangeset(i + 1)
if err != nil {
return err
}
c.changesets = append(c.changesets, *changeset)
i = newIndex
} else if lines[i] == rollbackAnnotation {
return errors.Errorf("unexpected rollback statement (line %v)", i+1)
} else if lines[i] != "" {
return errors.New("could not parse file")
}
}
return nil
}