Support drop index

lex/dialect_sql.go

@@ -461,6 +461,17 @@ func lexAs(l *Lexer) StateFn {
 	}
 	return nil
 }
+func lexOn(l *Lexer) StateFn {
+	l.SkipWhiteSpaces()
+	keyWord := strings.ToLower(l.PeekWord())
+	switch keyWord {
+	case "on":
+		l.ConsumeWord(keyWord)
+		l.Emit(TokenOn)
+		return nil
+	}
+	return nil
+}
 func lexNotExists(l *Lexer) StateFn {
 	l.SkipWhiteSpaces()
 	keyWord := strings.ToLower(l.PeekWord())
@@ -534,6 +545,9 @@ func LexDrop(l *Lexer) StateFn {
 	case "table":
 		l.ConsumeWord(keyWord)
 		l.Emit(TokenTable)
+	case "index":
+		l.ConsumeWord(keyWord)
+		l.Emit(TokenIndex)
 	case "source":
 		l.ConsumeWord(keyWord)
 		l.Emit(TokenSource)
@@ -553,6 +567,8 @@ func LexDrop(l *Lexer) StateFn {
 		return nil
 	}
 	l.Push("LexIdentifier", LexIdentifier)
+	l.Push("LexOn", lexOn)
+	l.Push("LexIdentifier", LexIdentifier)
 	return lexNotExists
 }
 

rel/parse_sql.go

@@ -860,28 +860,47 @@ func (m *Sqlbridge) parseDrop() (*SqlDrop, error) {
 		req.Temp = true
 	}
 
-	// DROP (TABLE|VIEW|SOURCE|CONTINUOUSVIEW) <identity>
+	// DROP (TABLE|VIEW|SOURCE|INDEX|CONTINUOUSVIEW) <identity>
 	switch m.Cur().T {
-	case lex.TokenTable, lex.TokenView, lex.TokenSource, lex.TokenContinuousView,
+	case lex.TokenTable, lex.TokenView, lex.TokenIndex, lex.TokenSource, lex.TokenContinuousView,
 		lex.TokenSchema, lex.TokenDatabase:
 		req.Tok = m.Next()
 	case lex.TokenIdentity:
 		// triggers, indexes
 		req.Tok = m.Next()
 	default:
-		return nil, m.ErrMsg("Expected view, database,schema, table, source, continuousview for DROP got")
+		return nil, m.ErrMsg("Expected view, database, index, schema, table, source, continuousview for DROP got")
+	}
+
+	if m.Cur().T == lex.TokenIf {
+		m.Next() // Consume IF
+		if m.Next().T != lex.TokenExists {
+			return nil, m.ErrMsg("Expected CREATE {TABLE|INDEX|SCHEMA|DATABASE} IF EXISTS <identity>")
+		}
+		req.IfExists = true
 	}
 
 	switch m.Cur().T {
 	case lex.TokenTable, lex.TokenIdentity:
 		req.Identity = m.Next().V
 	default:
-		return nil, m.ErrMsg("Expected identity after DROP (TABLE|VIEW|SOURCE|SCHEMA|DATABASE)  ")
+		return nil, m.ErrMsg("Expected identity after DROP (TABLE|INDEX|VIEW|SOURCE|SCHEMA|DATABASE)  ")
 	}
 
 	switch req.Tok.T {
 	case lex.TokenTable:
 		// just table
+	case lex.TokenIndex:
+		t := m.Next() // consume ON
+		if t.T != lex.TokenOn {
+			return nil, m.ErrMsg("Expected ON")
+		}
+		t = m.Next() // consume Identity
+		if t.T != lex.TokenIdentity {
+			return nil, m.ErrMsg("Expected Identity table name")
+		}
+		req.Parent = t.V
+		discardComments(m)
 	case lex.TokenSource, lex.TokenSchema:
 		// schema
 	case lex.TokenContinuousView, lex.TokenView:

rel/parse_sql_test.go

@@ -740,13 +740,35 @@ func TestSqlDrop(t *testing.T) {
 	t.Parallel()
 	sql := `DROP TABLE articles;`
 	req, err := rel.ParseSql(sql)
-	assert.Equal(t, nil, err)
-	assert.NotEqual(t, nil, req)
+	assert.NoError(t, err)
+	assert.NotNil(t, req)
 	ds, ok := req.(*rel.SqlDrop)
 	assert.True(t, ok, "wanted SqlDrop got %T", req)
 	assert.Equal(t, lex.TokenDrop, ds.Keyword(), "Has keyword DROP")
 	assert.Equal(t, "TABLE", ds.Tok.V, "Wanted TABLE: got %q", ds.Tok.V)
 	assert.Equal(t, "articles", ds.Identity, "has articles: %v", ds.Identity)
+
+	sql = `DROP INDEX idx_user_email ON users;`
+	req, err = rel.ParseSql(sql)
+	assert.NoError(t, err)
+	assert.NotNil(t, req)
+	ds, ok = req.(*rel.SqlDrop)
+	assert.True(t, ok, "wanted SqlDrop got %T", req)
+	assert.Equal(t, lex.TokenDrop, ds.Keyword(), "Has keyword DROP")
+	assert.Equal(t, "INDEX", ds.Tok.V, "Wanted INDEX: got %q", ds.Tok.V)
+	assert.Equal(t, "idx_user_email", ds.Identity, "has idx_user_email: %v", ds.Identity)
+
+	sql = `DROP INDEX IF EXISTS idx_user_name ON users;`
+	req, err = rel.ParseSql(sql)
+	assert.NoError(t, err)
+	assert.NotNil(t, req)
+	ds, ok = req.(*rel.SqlDrop)
+	assert.True(t, ok, "wanted SqlDrop got %T", req)
+	assert.Equal(t, lex.TokenDrop, ds.Keyword(), "Has keyword DROP")
+	assert.Equal(t, "INDEX", ds.Tok.V, "Wanted INDEX: got %q", ds.Tok.V)
+	assert.Equal(t, "idx_user_name", ds.Identity, "has idx_user_name: %v", ds.Identity)
+	assert.Equal(t, "users", ds.Parent, "has table users: %v", ds.Parent)
+	assert.True(t, ds.IfExists, "Expected IfExists to be true")
 }
 
 func TestWithNameValue(t *testing.T) {

rel/sql.go

@@ -221,6 +221,8 @@ type (
 		Temp     bool      // Temp?
 		Tok      lex.Token // DROP [TEMP] [TABLE,VIEW,CONTINUOUSVIEW,TRIGGER] etc
 		With     u.JsonHelper
+		IfExists bool
+		Parent   string
 	}
 	// SqlAlter SQL ALTER statement
 	SqlAlter struct {