schemadiff: supporting textual diff

go/vt/schemadiff/annotations.go

@@ -0,0 +1,239 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schemadiff
+
+import (
+	"strings"
+)
+
+// TextualAnnotationType is an enum for the type of annotation that can be applied to a line of text.
+type TextualAnnotationType int
+
+const (
+	UnchangedTextualAnnotationType TextualAnnotationType = iota
+	AddedTextualAnnotationType
+	RemovedTextualAnnotationType
+)
+
+// AnnotatedText is a some text and its annotation type. The text is usually single-line, but it
+// can be multi-line, as in the case of partition specs.
+type AnnotatedText struct {
+	text string
+	typ  TextualAnnotationType
+}
+
+// TextualAnnotations is a sequence of annotated texts. It is the annotated representation of a statement.
+type TextualAnnotations struct {
+	texts         []*AnnotatedText
+	hasAnyChanges bool
+}
+
+func NewTextualAnnotations() *TextualAnnotations {
+	return &TextualAnnotations{}
+}
+
+func (a *TextualAnnotations) Len() int {
+	return len(a.texts)
+}
+
+func (a *TextualAnnotations) mark(text string, typ TextualAnnotationType) {
+	a.texts = append(a.texts, &AnnotatedText{text: text, typ: typ})
+	if typ != UnchangedTextualAnnotationType {
+		a.hasAnyChanges = true
+	}
+}
+
+func (a *TextualAnnotations) MarkAdded(text string) {
+	a.mark(text, AddedTextualAnnotationType)
+}
+
+func (a *TextualAnnotations) MarkRemoved(text string) {
+	a.mark(text, RemovedTextualAnnotationType)
+}
+
+func (a *TextualAnnotations) MarkUnchanged(text string) {
+	a.mark(text, UnchangedTextualAnnotationType)
+}
+
+// ByType returns the subset of annotations by given type.
+func (a *TextualAnnotations) ByType(typ TextualAnnotationType) (r []*AnnotatedText) {
+	for _, text := range a.texts {
+		if text.typ == typ {
+			r = append(r, text)
+		}
+	}
+	return r
+}
+
+func (a *TextualAnnotations) Added() (r []*AnnotatedText) {
+	return a.ByType(AddedTextualAnnotationType)
+}
+
+func (a *TextualAnnotations) Removed() (r []*AnnotatedText) {
+	return a.ByType(RemovedTextualAnnotationType)
+}
+
+// Export beautifies the annotated text and returns it as a string.
+func (a *TextualAnnotations) Export() string {
+	textLines := make([]string, 0, len(a.texts))
+	for _, annotatedText := range a.texts {
+		switch annotatedText.typ {
+		case AddedTextualAnnotationType:
+			annotatedText.text = "+" + annotatedText.text
+		case RemovedTextualAnnotationType:
+			annotatedText.text = "-" + annotatedText.text
+		default:
+			// text unchanged
+			if a.hasAnyChanges {
+				// If there is absolutely no change, we don't add a space anywhere
+				annotatedText.text = " " + annotatedText.text
+			}
+		}
+		textLines = append(textLines, annotatedText.text)
+	}
+	return strings.Join(textLines, "\n")
+}
+
+// annotatedStatement returns a new TextualAnnotations object that annotates the given statement with the given annotations.
+// The given annotations were created by the diffing algorithm, and represent the CanonicalString of some node.
+// However, the given statement is just some text, and we need to find the annotations (some of which may be multi-line)
+// inside our text, and return a per-line annotation.
+func annotatedStatement(stmt string, annotationType TextualAnnotationType, annotations *TextualAnnotations) *TextualAnnotations {
+	stmtLines := strings.Split(stmt, "\n")
+	result := NewTextualAnnotations()
+	annotationLines := map[string]bool{} // single-line breakdown of all annotations
+	for _, annotation := range annotations.ByType(annotationType) {
+		// An annotated text could be multiline. Partition specs are such.
+		lines := strings.Split(annotation.text, "\n")
+		for _, line := range lines {
+			line = strings.TrimSpace(line)
+			if line != "" {
+				annotationLines[line] = true
+			}
+		}
+	}
+	annotationLinesMutations := map[string](map[string]bool){}
+	// Mutations are expected ways to find an annotation inside a `CREATE TABLE` statement.
+	for annotationLine := range annotationLines {
+		possibleMutations := map[string]bool{
+			annotationLine:              true,
+			") " + annotationLine:       true, // e.g. ") ENGINE=InnoDB"
+			") " + annotationLine + ",": true, // e.g. ") ENGINE=InnoDB,[\n	 ROW_FORMAT=COMPRESSED]"
+			"(" + annotationLine + ")":  true, // e.g. "(PARTITION p0 VALUES LESS THAN (10))
+			"(" + annotationLine + ",":  true, // e.g. "(PARTITION p0 VALUES LESS THAN (10),
+			annotationLine + ",":        true, // e.g. "i int unsigned,"
+			annotationLine + ")":        true, // e.g. "PARTITION p9 VALUES LESS THAN (90))"
+		}
+		annotationLinesMutations[annotationLine] = possibleMutations
+	}
+	for i := range stmtLines {
+		lineAnnotated := false
+		trimmedLine := strings.TrimSpace(stmtLines[i])
+		if trimmedLine == "" {
+			continue
+		}
+		for annotationLine := range annotationLines {
+			if lineAnnotated {
+				break
+			}
+			possibleMutations := annotationLinesMutations[annotationLine]
+			if possibleMutations[trimmedLine] {
+				// Annotate this line!
+				result.mark(stmtLines[i], annotationType)
+				lineAnnotated = true
+				// No need to match this annotation again
+				delete(annotationLines, annotationLine)
+				delete(possibleMutations, annotationLine)
+			}
+		}
+		if !lineAnnotated {
+			result.MarkUnchanged(stmtLines[i])
+		}
+	}
+	return result
+}
+
+// annotateAll blindly annotates all lines of the given statement with the given annotation type.
+func annotateAll(stmt string, annotationType TextualAnnotationType) *TextualAnnotations {
+	stmtLines := strings.Split(stmt, "\n")
+	result := NewTextualAnnotations()
+	for _, line := range stmtLines {
+		result.mark(line, annotationType)
+	}
+	return result
+}
+
+// unifiedAnnotated takes two annotations of from, to statements and returns a unified annotation.
+func unifiedAnnotated(from *TextualAnnotations, to *TextualAnnotations) *TextualAnnotations {
+	unified := NewTextualAnnotations()
+	fromIndex := 0
+	toIndex := 0
+	for fromIndex < from.Len() || toIndex < to.Len() {
+		matchingLine := ""
+		if fromIndex < from.Len() {
+			fromLine := from.texts[fromIndex]
+			if fromLine.typ == RemovedTextualAnnotationType {
+				unified.MarkRemoved(fromLine.text)
+				fromIndex++
+				continue
+			}
+			matchingLine = fromLine.text
+		}
+		if toIndex < to.Len() {
+			toLine := to.texts[toIndex]
+			if toLine.typ == AddedTextualAnnotationType {
+				unified.MarkAdded(toLine.text)
+				toIndex++
+				continue
+			}
+			if matchingLine == "" {
+				matchingLine = toLine.text
+			}
+		}
+		unified.MarkUnchanged(matchingLine)
+		fromIndex++
+		toIndex++
+	}
+	return unified
+}
+
+// annotatedDiff returns the annotated representations of the from and to entities, and their unified representation.
+func annotatedDiff(diff EntityDiff, entityAnnotations *TextualAnnotations) (from *TextualAnnotations, to *TextualAnnotations, unified *TextualAnnotations) {
+	fromEntity, toEntity := diff.Entities()
+	switch {
+	case fromEntity == nil && toEntity == nil:
+		// Should never get here.
+		return nil, nil, nil
+	case fromEntity == nil:
+		// A new entity was created.
+		from = NewTextualAnnotations()
+		to = annotateAll(toEntity.Create().CanonicalStatementString(), AddedTextualAnnotationType)
+	case toEntity == nil:
+		// An entity was dropped.
+		from = annotateAll(fromEntity.Create().CanonicalStatementString(), RemovedTextualAnnotationType)
+		to = NewTextualAnnotations()
+	case entityAnnotations == nil:
+		// Entity was modified, and we have no prior info about entity annotations. Treat this is as a complete rewrite.
+		from = annotateAll(fromEntity.Create().CanonicalStatementString(), RemovedTextualAnnotationType)
+		to = annotateAll(toEntity.Create().CanonicalStatementString(), AddedTextualAnnotationType)
+	default:
+		// Entity was modified, and we have prior info about entity annotations.
+		from = annotatedStatement(fromEntity.Create().CanonicalStatementString(), RemovedTextualAnnotationType, entityAnnotations)
+		to = annotatedStatement(toEntity.Create().CanonicalStatementString(), AddedTextualAnnotationType, entityAnnotations)
+	}
+	return from, to, unifiedAnnotated(from, to)
+}

go/vt/schemadiff/annotations_test.go

@@ -0,0 +1,102 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schemadiff
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"vitess.io/vitess/go/vt/sqlparser"
+)
+
+func TestAnnotateAll(t *testing.T) {
+	stmt := `create table t(
+	id int,
+	name varchar(100),
+	primary key(id)
+) engine=innodb`
+	annotations := annotateAll(stmt, RemovedTextualAnnotationType)
+	assert.Equal(t, 5, annotations.Len())
+	expect := `-create table t(
+-	id int,
+-	name varchar(100),
+-	primary key(id)
+-) engine=innodb`
+	assert.Equal(t, expect, annotations.Export())
+}
+
+func TestUnifiedAnnotated(t *testing.T) {
+	tcases := []struct {
+		name            string
+		from            string
+		to              string
+		fromAnnotations *TextualAnnotations
+		toAnnotations   *TextualAnnotations
+		expected        string
+	}{
+		{
+			"no change",
+			"CREATE TABLE t1 (a int)",
+			"CREATE TABLE t1 (a int)",
+			&TextualAnnotations{},
+			&TextualAnnotations{},
+			"CREATE TABLE `t1` (\n\t`a` int\n)",
+		},
+		{
+			"simple",
+			"CREATE TABLE t1 (a int)",
+			"CREATE TABLE t1 (a int, b int)",
+			&TextualAnnotations{},
+			&TextualAnnotations{texts: []*AnnotatedText{{text: "`b` int", typ: AddedTextualAnnotationType}}},
+			" CREATE TABLE `t1` (\n \t`a` int\n+\t`b` int\n )",
+		},
+	}
+	parser := sqlparser.NewTestParser()
+
+	for _, tcase := range tcases {
+		t.Run(tcase.name, func(t *testing.T) {
+			fromStmt, err := parser.ParseStrictDDL(tcase.from)
+			require.NoError(t, err)
+			annotatedFrom := annotatedStatement(sqlparser.CanonicalString(fromStmt), RemovedTextualAnnotationType, tcase.fromAnnotations)
+			toStmt, err := parser.ParseStrictDDL(tcase.to)
+			require.NoError(t, err)
+			annotatedTo := annotatedStatement(sqlparser.CanonicalString(toStmt), AddedTextualAnnotationType, tcase.toAnnotations)
+			unified := unifiedAnnotated(annotatedFrom, annotatedTo)
+			export := unified.Export()
+			assert.Equalf(t, tcase.expected, export, "from: %v, to: %v", annotatedFrom.Export(), annotatedTo.Export())
+		})
+	}
+}
+
+func TestUnifiedAnnotatedAll(t *testing.T) {
+	stmt := `create table t(
+	id int,
+	name varchar(100),
+	primary key(id)
+) engine=innodb`
+	annotatedTo := annotateAll(stmt, AddedTextualAnnotationType)
+	annotatedFrom := NewTextualAnnotations()
+	unified := unifiedAnnotated(annotatedFrom, annotatedTo)
+	expect := `+create table t(
++	id int,
++	name varchar(100),
++	primary key(id)
++) engine=innodb`
+	assert.Equal(t, expect, unified.Export())
+}