package compiler
import (
"fmt"
"github.com/d5/tengo/objects"
)
// RemoveDuplicates finds and remove the duplicate values in Constants.
// Note this function mutates Bytecode.
func (b *Bytecode) RemoveDuplicates() {
var deduped []objects.Object
indexMap := make(map[int]int) // mapping from old constant index to new index
ints := make(map[int64]int)
strings := make(map[string]int)
floats := make(map[float64]int)
chars := make(map[rune]int)
immutableMaps := make(map[string]int) // for modules
for curIdx, c := range b.Constants {
switch c := c.(type) {
case *objects.CompiledFunction:
// add to deduped list
indexMap[curIdx] = len(deduped)
deduped = append(deduped, c)
case *objects.ImmutableMap:
modName := moduleName(c)
newIdx, ok := immutableMaps[modName]
if modName != "" && ok {
indexMap[curIdx] = newIdx
} else {
newIdx = len(deduped)
immutableMaps[modName] = newIdx
indexMap[curIdx] = newIdx
deduped = append(deduped, c)
}
case *objects.Int:
if newIdx, ok := ints[c.Value]; ok {
indexMap[curIdx] = newIdx
} else {
newIdx = len(deduped)
ints[c.Value] = newIdx
indexMap[curIdx] = newIdx
deduped = append(deduped, c)
}
case *objects.String:
if newIdx, ok := strings[c.Value]; ok {
indexMap[curIdx] = newIdx
} else {
newIdx = len(deduped)
strings[c.Value] = newIdx
indexMap[curIdx] = newIdx
deduped = append(deduped, c)
}
case *objects.Float:
if newIdx, ok := floats[c.Value]; ok {
indexMap[curIdx] = newIdx
} else {
newIdx = len(deduped)
floats[c.Value] = newIdx
indexMap[curIdx] = newIdx
deduped = append(deduped, c)
}
case *objects.Char:
if newIdx, ok := chars[c.Value]; ok {
indexMap[curIdx] = newIdx
} else {
newIdx = len(deduped)
chars[c.Value] = newIdx
indexMap[curIdx] = newIdx
deduped = append(deduped, c)
}
default:
panic(fmt.Errorf("unsupported top-level constant type: %s", c.TypeName()))
}
}
// replace with de-duplicated constants
b.Constants = deduped
// update CONST instructions with new indexes
// main function
updateConstIndexes(b.MainFunction.Instructions, indexMap)
// other compiled functions in constants
for _, c := range b.Constants {
switch c := c.(type) {
case *objects.CompiledFunction:
updateConstIndexes(c.Instructions, indexMap)
}
}
}
func updateConstIndexes(insts []byte, indexMap map[int]int) {
i := 0
for i < len(insts) {
op := insts[i]
numOperands := OpcodeOperands[op]
_, read := ReadOperands(numOperands, insts[i+1:])
switch op {
case OpConstant:
curIdx := int(insts[i+2]) | int(insts[i+1])<<8
newIdx, ok := indexMap[curIdx]
if !ok {
panic(fmt.Errorf("constant index not found: %d", curIdx))
}
copy(insts[i:], MakeInstruction(op, newIdx))
case OpClosure:
curIdx := int(insts[i+2]) | int(insts[i+1])<<8
numFree := int(insts[i+3])
newIdx, ok := indexMap[curIdx]
if !ok {
panic(fmt.Errorf("constant index not found: %d", curIdx))
}
copy(insts[i:], MakeInstruction(op, newIdx, numFree))
}
i += 1 + read
}
}
func moduleName(mod *objects.ImmutableMap) string {
if modName, ok := mod.Value["__module_name__"].(*objects.String); ok {
return modName.Value
}
return ""
}