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parser.go
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/
parser.go
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// Copyright 2019 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package metamorphic
import (
"fmt"
"go/scanner"
"go/token"
"reflect"
"strconv"
"strings"
"github.com/cockroachdb/errors"
"github.com/patrick-ogrady/pebble"
)
type methodInfo struct {
constructor func() op
validTags uint32
}
func makeMethod(i interface{}, tags ...objTag) *methodInfo {
var validTags uint32
for _, tag := range tags {
validTags |= 1 << tag
}
t := reflect.TypeOf(i)
return &methodInfo{
constructor: func() op {
return reflect.New(t).Interface().(op)
},
validTags: validTags,
}
}
// args returns the receiverID, targetID and arguments for the op. The
// receiverID is the ID of the object the op will be applied to. The targetID
// is the ID of the object for assignment. If the method does not return a new
// object, then targetID will be nil. The argument list is just what it sounds
// like: the list of arguments for the operation.
func opArgs(op op) (receiverID *objID, targetID *objID, args []interface{}) {
switch t := op.(type) {
case *applyOp:
return &t.writerID, nil, []interface{}{&t.batchID}
case *checkpointOp:
return nil, nil, []interface{}{&t.spans}
case *closeOp:
return &t.objID, nil, nil
case *compactOp:
return nil, nil, []interface{}{&t.start, &t.end, &t.parallelize}
case *batchCommitOp:
return &t.batchID, nil, nil
case *dbRatchetFormatMajorVersionOp:
return nil, nil, []interface{}{&t.vers}
case *dbRestartOp:
return nil, nil, nil
case *deleteOp:
return &t.writerID, nil, []interface{}{&t.key}
case *deleteRangeOp:
return &t.writerID, nil, []interface{}{&t.start, &t.end}
case *iterFirstOp:
return &t.iterID, nil, nil
case *flushOp:
return nil, nil, nil
case *getOp:
return &t.readerID, nil, []interface{}{&t.key}
case *ingestOp:
return nil, nil, []interface{}{&t.batchIDs}
case *initOp:
return nil, nil, []interface{}{&t.batchSlots, &t.iterSlots, &t.snapshotSlots}
case *iterLastOp:
return &t.iterID, nil, nil
case *mergeOp:
return &t.writerID, nil, []interface{}{&t.key, &t.value}
case *newBatchOp:
return nil, &t.batchID, nil
case *newIndexedBatchOp:
return nil, &t.batchID, nil
case *newIterOp:
return &t.readerID, &t.iterID, []interface{}{&t.lower, &t.upper, &t.keyTypes, &t.filterMin, &t.filterMax, &t.useL6Filters, &t.maskSuffix}
case *newIterUsingCloneOp:
return &t.existingIterID, &t.iterID, []interface{}{&t.refreshBatch, &t.lower, &t.upper, &t.keyTypes, &t.filterMin, &t.filterMax, &t.useL6Filters, &t.maskSuffix}
case *newSnapshotOp:
return nil, &t.snapID, []interface{}{&t.bounds}
case *iterNextOp:
return &t.iterID, nil, []interface{}{&t.limit}
case *iterNextPrefixOp:
return &t.iterID, nil, nil
case *iterCanSingleDelOp:
return &t.iterID, nil, []interface{}{}
case *iterPrevOp:
return &t.iterID, nil, []interface{}{&t.limit}
case *iterSeekLTOp:
return &t.iterID, nil, []interface{}{&t.key, &t.limit}
case *iterSeekGEOp:
return &t.iterID, nil, []interface{}{&t.key, &t.limit}
case *iterSeekPrefixGEOp:
return &t.iterID, nil, []interface{}{&t.key}
case *setOp:
return &t.writerID, nil, []interface{}{&t.key, &t.value}
case *iterSetBoundsOp:
return &t.iterID, nil, []interface{}{&t.lower, &t.upper}
case *iterSetOptionsOp:
return &t.iterID, nil, []interface{}{&t.lower, &t.upper, &t.keyTypes, &t.filterMin, &t.filterMax, &t.useL6Filters, &t.maskSuffix}
case *singleDeleteOp:
return &t.writerID, nil, []interface{}{&t.key, &t.maybeReplaceDelete}
case *rangeKeyDeleteOp:
return &t.writerID, nil, []interface{}{&t.start, &t.end}
case *rangeKeySetOp:
return &t.writerID, nil, []interface{}{&t.start, &t.end, &t.suffix, &t.value}
case *rangeKeyUnsetOp:
return &t.writerID, nil, []interface{}{&t.start, &t.end, &t.suffix}
}
panic(fmt.Sprintf("unsupported op type: %T", op))
}
var methods = map[string]*methodInfo{
"Apply": makeMethod(applyOp{}, dbTag, batchTag),
"Checkpoint": makeMethod(checkpointOp{}, dbTag),
"Clone": makeMethod(newIterUsingCloneOp{}, iterTag),
"Close": makeMethod(closeOp{}, dbTag, batchTag, iterTag, snapTag),
"Commit": makeMethod(batchCommitOp{}, batchTag),
"Compact": makeMethod(compactOp{}, dbTag),
"Delete": makeMethod(deleteOp{}, dbTag, batchTag),
"DeleteRange": makeMethod(deleteRangeOp{}, dbTag, batchTag),
"First": makeMethod(iterFirstOp{}, iterTag),
"Flush": makeMethod(flushOp{}, dbTag),
"Get": makeMethod(getOp{}, dbTag, batchTag, snapTag),
"Ingest": makeMethod(ingestOp{}, dbTag),
"Init": makeMethod(initOp{}, dbTag),
"Last": makeMethod(iterLastOp{}, iterTag),
"Merge": makeMethod(mergeOp{}, dbTag, batchTag),
"NewBatch": makeMethod(newBatchOp{}, dbTag),
"NewIndexedBatch": makeMethod(newIndexedBatchOp{}, dbTag),
"NewIter": makeMethod(newIterOp{}, dbTag, batchTag, snapTag),
"NewSnapshot": makeMethod(newSnapshotOp{}, dbTag),
"Next": makeMethod(iterNextOp{}, iterTag),
"NextPrefix": makeMethod(iterNextPrefixOp{}, iterTag),
"InternalNext": makeMethod(iterCanSingleDelOp{}, iterTag),
"Prev": makeMethod(iterPrevOp{}, iterTag),
"RangeKeyDelete": makeMethod(rangeKeyDeleteOp{}, dbTag, batchTag),
"RangeKeySet": makeMethod(rangeKeySetOp{}, dbTag, batchTag),
"RangeKeyUnset": makeMethod(rangeKeyUnsetOp{}, dbTag, batchTag),
"RatchetFormatMajorVersion": makeMethod(dbRatchetFormatMajorVersionOp{}, dbTag),
"Restart": makeMethod(dbRestartOp{}, dbTag),
"SeekGE": makeMethod(iterSeekGEOp{}, iterTag),
"SeekLT": makeMethod(iterSeekLTOp{}, iterTag),
"SeekPrefixGE": makeMethod(iterSeekPrefixGEOp{}, iterTag),
"Set": makeMethod(setOp{}, dbTag, batchTag),
"SetBounds": makeMethod(iterSetBoundsOp{}, iterTag),
"SetOptions": makeMethod(iterSetOptionsOp{}, iterTag),
"SingleDelete": makeMethod(singleDeleteOp{}, dbTag, batchTag),
}
type parser struct {
fset *token.FileSet
s scanner.Scanner
objs map[objID]bool
}
func parse(src []byte) (_ []op, err error) {
// Various bits of magic incantation to set up a scanner for Go compatible
// syntax. We arranged for the textual format of ops (e.g. op.String()) to
// look like Go which allows us to use the Go scanner for parsing.
p := &parser{
fset: token.NewFileSet(),
objs: map[objID]bool{makeObjID(dbTag, 0): true},
}
file := p.fset.AddFile("", -1, len(src))
p.s.Init(file, src, nil /* no error handler */, 0)
return p.parse()
}
func (p *parser) parse() (_ []op, err error) {
defer func() {
if r := recover(); r != nil {
var ok bool
if err, ok = r.(error); ok {
return
}
err = errors.Errorf("%v", r)
}
}()
var ops []op
for {
op := p.parseOp()
if op == nil {
computeDerivedFields(ops)
return ops, nil
}
ops = append(ops, op)
}
}
func (p *parser) parseOp() op {
destPos, destTok, destLit := p.s.Scan()
if destTok == token.EOF {
return nil
}
if destTok != token.IDENT {
panic(p.errorf(destPos, "unexpected token: %s %q", destTok, destLit))
}
if destLit == "Init" {
// <op>(<args>)
return p.makeOp(destLit, makeObjID(dbTag, 0), 0, destPos)
}
destID := p.parseObjID(destPos, destLit)
pos, tok, lit := p.s.Scan()
switch tok {
case token.PERIOD:
// <obj>.<op>(<args>)
if !p.objs[destID] {
panic(p.errorf(destPos, "unknown object: %s", destID))
}
_, methodLit := p.scanToken(token.IDENT)
return p.makeOp(methodLit, destID, 0, destPos)
case token.ASSIGN:
// <obj> = <obj>.<op>(<args>)
srcPos, srcLit := p.scanToken(token.IDENT)
srcID := p.parseObjID(srcPos, srcLit)
if !p.objs[srcID] {
panic(p.errorf(srcPos, "unknown object %q", srcLit))
}
p.scanToken(token.PERIOD)
_, methodLit := p.scanToken(token.IDENT)
p.objs[destID] = true
return p.makeOp(methodLit, srcID, destID, srcPos)
}
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
func (p *parser) parseObjID(pos token.Pos, str string) objID {
var tag objTag
switch {
case str == "db":
return makeObjID(dbTag, 0)
case strings.HasPrefix(str, "batch"):
tag, str = batchTag, str[5:]
case strings.HasPrefix(str, "iter"):
tag, str = iterTag, str[4:]
case strings.HasPrefix(str, "snap"):
tag, str = snapTag, str[4:]
default:
panic(p.errorf(pos, "unable to parse objectID: %q", str))
}
id, err := strconv.ParseInt(str, 10, 32)
if err != nil {
panic(p.errorf(pos, "%s", err))
}
return makeObjID(tag, uint32(id))
}
func unquoteBytes(lit string) []byte {
s, err := strconv.Unquote(lit)
if err != nil {
panic(err)
}
if len(s) == 0 {
return nil
}
return []byte(s)
}
func (p *parser) parseArgs(op op, methodName string, args []interface{}) {
pos, _ := p.scanToken(token.LPAREN)
for i := range args {
if i > 0 {
pos, _ = p.scanToken(token.COMMA)
}
switch t := args[i].(type) {
case *uint32:
_, lit := p.scanToken(token.INT)
val, err := strconv.ParseUint(lit, 10, 32)
if err != nil {
panic(err)
}
*t = uint32(val)
case *uint64:
_, lit := p.scanToken(token.INT)
val, err := strconv.ParseUint(lit, 10, 64)
if err != nil {
panic(err)
}
*t = uint64(val)
case *[]byte:
_, lit := p.scanToken(token.STRING)
*t = unquoteBytes(lit)
case *bool:
_, lit := p.scanToken(token.IDENT)
b, err := strconv.ParseBool(lit)
if err != nil {
panic(err)
}
*t = b
case *objID:
pos, lit := p.scanToken(token.IDENT)
*t = p.parseObjID(pos, lit)
case *[]pebble.KeyRange:
var pending pebble.KeyRange
for {
pos, tok, lit := p.s.Scan()
switch tok {
case token.STRING:
x := unquoteBytes(lit)
if pending.Start == nil {
pending.Start = x
} else {
pending.End = x
*t = append(*t, pending)
pending = pebble.KeyRange{}
}
pos, tok, lit := p.s.Scan()
switch tok {
case token.COMMA:
continue
case token.RPAREN:
p.scanToken(token.SEMICOLON)
return
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
case token.RPAREN:
p.scanToken(token.SEMICOLON)
return
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
}
case *[]objID:
for {
pos, tok, lit := p.s.Scan()
switch tok {
case token.IDENT:
*t = append(*t, p.parseObjID(pos, lit))
pos, tok, lit := p.s.Scan()
switch tok {
case token.COMMA:
continue
case token.RPAREN:
p.scanToken(token.SEMICOLON)
return
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
case token.RPAREN:
p.scanToken(token.SEMICOLON)
return
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
}
case *[]pebble.CheckpointSpan:
pos, tok, lit := p.s.Scan()
switch tok {
case token.RPAREN:
// No spans.
*t = nil
p.scanToken(token.SEMICOLON)
return
case token.STRING:
var keys [][]byte
for {
s, err := strconv.Unquote(lit)
if err != nil {
panic(p.errorf(pos, "unquoting %q: %v", lit, err))
}
keys = append(keys, []byte(s))
pos, tok, lit = p.s.Scan()
switch tok {
case token.COMMA:
pos, tok, lit = p.s.Scan()
if tok != token.STRING {
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
continue
case token.RPAREN:
p.scanToken(token.SEMICOLON)
if len(keys)%2 == 1 {
panic(p.errorf(pos, "expected even number of keys"))
}
*t = make([]pebble.CheckpointSpan, len(keys)/2)
for i := range *t {
(*t)[i] = pebble.CheckpointSpan{
Start: keys[i*2],
End: keys[i*2+1],
}
}
return
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
}
default:
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
case *pebble.FormatMajorVersion:
_, lit := p.scanToken(token.INT)
val, err := strconv.ParseUint(lit, 10, 64)
if err != nil {
panic(err)
}
*t = pebble.FormatMajorVersion(val)
default:
panic(p.errorf(pos, "%s: unsupported arg[%d] type: %T", methodName, i, args[i]))
}
}
p.scanToken(token.RPAREN)
p.scanToken(token.SEMICOLON)
}
func (p *parser) scanToken(expected token.Token) (pos token.Pos, lit string) {
pos, tok, lit := p.s.Scan()
if tok != expected {
panic(p.errorf(pos, "unexpected token: %q", p.tokenf(tok, lit)))
}
return pos, lit
}
func (p *parser) makeOp(methodName string, receiverID, targetID objID, pos token.Pos) op {
info := methods[methodName]
if info == nil {
panic(p.errorf(pos, "unknown op %s.%s", receiverID, methodName))
}
if info.validTags&(1<<receiverID.tag()) == 0 {
panic(p.errorf(pos, "%s.%s: %s is not a method on %s",
receiverID, methodName, methodName, receiverID))
}
op := info.constructor()
receiver, target, args := opArgs(op)
// The form of an operation is:
// [target =] receiver.method(args)
//
// The receiver is the object the operation will be called on, which can be
// any valid ID. Certain operations such as Ingest are only valid on the DB
// object. That is indicated by opArgs returning a nil receiver.
if receiver != nil {
*receiver = receiverID
} else if receiverID.tag() != dbTag {
panic(p.errorf(pos, "unknown op %s.%s", receiverID, methodName))
}
// The target is the object that will be assigned the result of an object
// creation operation such as newBatchOp or newIterOp.
if target != nil {
// It is invalid to not have a targetID for a method which generates a new
// object.
if targetID == 0 {
panic(p.errorf(pos, "assignment expected for %s.%s", receiverID, methodName))
}
// It is invalid to try to assign to the DB object.
if targetID.tag() == dbTag {
panic(p.errorf(pos, "cannot use %s as target of assignment", targetID))
}
*target = targetID
} else if targetID != 0 {
panic(p.errorf(pos, "cannot use %s.%s in assignment", receiverID, methodName))
}
p.parseArgs(op, methodName, args)
return op
}
func (p *parser) tokenf(tok token.Token, lit string) string {
if tok.IsLiteral() {
return lit
}
return tok.String()
}
func (p *parser) errorf(pos token.Pos, format string, args ...interface{}) error {
return errors.New(p.fset.Position(pos).String() + ": " + fmt.Sprintf(format, args...))
}
// computeDerivedFields makes one pass through the provided operations, filling
// any derived fields. This pass must happen before execution because concurrent
// execution depends on these fields.
func computeDerivedFields(ops []op) {
iterToReader := make(map[objID]objID)
for i := range ops {
switch v := ops[i].(type) {
case *newIterOp:
iterToReader[v.iterID] = v.readerID
case *newIterUsingCloneOp:
v.derivedReaderID = iterToReader[v.existingIterID]
iterToReader[v.iterID] = v.derivedReaderID
case *iterSetOptionsOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterFirstOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterLastOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterSeekGEOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterSeekPrefixGEOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterSeekLTOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterNextOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterNextPrefixOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterCanSingleDelOp:
v.derivedReaderID = iterToReader[v.iterID]
case *iterPrevOp:
v.derivedReaderID = iterToReader[v.iterID]
}
}
}