wehub-resource-sync
91 lines
3.0 KiB
Go
91 lines
3.0 KiB
Go
// Copyright 2025 Dolthub, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package plpgsql
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import (
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"github.com/cockroachdb/errors"
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"github.com/dolthub/doltgresql/utils"
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)
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// labelStackItem is the stack item used while reconciling labels.
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type labelStackItem struct {
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label string
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start int
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isLoop bool
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}
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// reconcileLabels handles all GOTO operations that may point to a label, since labels may be nested/shadowed. It's
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// easier to perform this is a final step, rather than trying to reconcile them during the operation conversion step.
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func reconcileLabels(ops []InterpreterOperation) error {
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labels := utils.NewStack[labelStackItem]()
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gotos := make(map[int]*InterpreterOperation)
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for opIndex, operation := range ops {
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switch operation.OpCode {
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case OpCode_Goto:
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// When this is true, we have a label
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if len(operation.PrimaryData) > 0 {
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if operation.Index < 0 {
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// This is a CONTINUE, so we already know the index that we need to go to
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found := false
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for i := 0; i < labels.Len(); i++ {
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stackItem := labels.PeekDepth(i)
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if stackItem.label == operation.PrimaryData {
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if !stackItem.isLoop {
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return errors.New("CONTINUE cannot be used outside a loop")
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}
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found = true
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ops[opIndex].Index = stackItem.start
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ops[opIndex].PrimaryData = ""
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break
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}
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}
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if !found {
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return errors.Errorf(`there is no label "%s" attached to any block or loop enclosing this statement`, operation.PrimaryData)
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}
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} else {
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// This is an EXIT, so we'll save it for later
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gotos[opIndex] = &ops[opIndex]
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}
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}
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case OpCode_ScopeBegin:
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// We'll push the label and loop status to the stack
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labels.Push(labelStackItem{
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label: operation.PrimaryData,
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start: opIndex + 1, // We want to go to the operation after this one, else we'll continually increase the scope
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isLoop: len(operation.Target) > 0,
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})
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// We clear the label and loop status since we only set them for reconciliation
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ops[opIndex].PrimaryData = ""
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ops[opIndex].Target = ""
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case OpCode_ScopeEnd:
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stackItem := labels.Pop()
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for gotoIdx, gotoOp := range gotos {
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if gotoOp.PrimaryData == stackItem.label {
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gotoOp.Index = opIndex // We want to go to this operation, as we want to exit the scope
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gotoOp.PrimaryData = ""
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delete(gotos, gotoIdx)
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}
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}
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}
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}
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if len(gotos) > 0 {
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for _, op := range gotos {
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return errors.Errorf(`there is no label "%s" attached to any block or loop enclosing this statement`, op.PrimaryData)
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}
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}
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return nil
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}
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