add begin parsing and handling

Author: withinboredom

atlas/socket/begin.go

@@ -0,0 +1,155 @@
+/*
+ * This file is part of Atlas-DB.
+ *
+ * Atlas-DB is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * Atlas-DB is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Atlas-DB. If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+package socket
+
+import (
+	"errors"
+	"github.com/bottledcode/atlas-db/atlas/commands"
+	"strings"
+)
+
+type Begin struct {
+	isReadonly bool
+	tables     []string
+	views      []string
+	triggers   []string
+}
+
+func sanitizeBegin(cmd commands.Command) (tables, views, triggers []string, err error) {
+	extractList := func() (list []string, err error) {
+		var rip []string
+		n := 4
+		expectingFirst := true
+		expectingLast := true
+		for {
+			first, _ := cmd.SelectNormalizedCommand(n)
+			rip = append(rip, first)
+			n++
+			isLast := false
+			first = strings.TrimSuffix(first, ",")
+			if first == "" {
+				break
+			}
+			if first == "(" {
+				expectingFirst = false
+				continue
+			}
+			if first == ")" {
+				expectingLast = false
+				break
+			}
+			if strings.HasPrefix(first, "(") {
+				first = strings.TrimPrefix(first, "(")
+				expectingFirst = false
+			}
+			if strings.HasSuffix(first, ")") {
+				expectingLast = false
+				first = strings.TrimSuffix(first, ")")
+				isLast = true
+			}
+			if expectingFirst {
+				err = errors.New("expected table name in parentheses")
+				return
+			}
+
+			if first == "," {
+				continue
+			}
+
+			list = append(list, cmd.NormalizeName(first))
+			if isLast {
+				break
+			}
+		}
+		if expectingFirst || expectingLast {
+			err = errors.New("expected table name in parentheses")
+			return
+		}
+		cmd = cmd.ReplaceCommand(strings.Join(rip, " "), "BEGIN IMMEDIATE WITH")
+		return
+	}
+
+	if t, ok := cmd.SelectNormalizedCommand(1); ok && t == "IMMEDIATE" {
+		if err = cmd.CheckMinLen(3); err != nil {
+			return
+		}
+		for {
+			switch t, _ = cmd.SelectNormalizedCommand(3); t {
+			case "TABLE":
+				if err = cmd.CheckMinLen(4); err != nil {
+					return
+				}
+				tables, err = extractList()
+				if err != nil {
+					return
+				}
+			case "VIEW":
+				if err = cmd.CheckMinLen(4); err != nil {
+					return
+				}
+				views, err = extractList()
+				if err != nil {
+					return
+				}
+			case "TRIGGER":
+				if err = cmd.CheckMinLen(4); err != nil {
+					return
+				}
+				triggers, err = extractList()
+				if err != nil {
+					return
+				}
+			case "":
+				return
+			default:
+				err = errors.New("expected TABLE, VIEW, or TRIGGER")
+				return
+			}
+		}
+	}
+	return
+}
+
+func ParseBegin(cmd commands.Command) (*Begin, error) {
+	if t, ok := cmd.SelectNormalizedCommand(1); ok && t == "IMMEDIATE" {
+		tables, views, triggers, err := sanitizeBegin(cmd)
+		if err != nil {
+			return nil, err
+		}
+
+		return &Begin{
+			isReadonly: false,
+			tables:     tables,
+			views:      views,
+			triggers:   triggers,
+		}, nil
+	}
+	return &Begin{
+		isReadonly: true,
+	}, nil
+}
+
+func (b *Begin) Handle(s *Socket) error {
+	s.authorizer.Reset()
+	s.authorizer.ForceReadonly = b.isReadonly
+
+	// todo: capture tables, views, and triggers
+
+	return nil
+}