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Eprx now supports range of indeces to extract parts of strings or lists

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This commit is contained in:
Celestino Amoroso
2024-05-26 06:19:08 +02:00
parent 691c213d17
commit 2c87d6bf9e
6 changed files with 215 additions and 53 deletions
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operator-index.go
+66 -31
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@@ -16,20 +16,14 @@ func newIndexTerm(tk *Token) (inst *term) {
}
func verifyKey(indexTerm *term, indexList *ListType) (index any, err error) {
if len(*indexList) != 1 {
err = indexTerm.Errorf("one index only is allowed")
} else {
index = (*indexList)[0]
}
index = (*indexList)[0]
return
}
func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int, err error) {
var v int
if len(*indexList) != 1 {
err = indexTerm.Errorf("one index only is allowed")
} else if v, err = toInt((*indexList)[0], "index expression"); err == nil {
if v, err = toInt((*indexList)[0], "index expression"); err == nil {
if v < 0 && v >= -maxValue {
v = maxValue + v
}
@@ -42,45 +36,86 @@ func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int,
return
}
func verifyRange(indexTerm *term, indexList *ListType, maxValue int) (startIndex, endIndex int, err error) {
v, _ := ((*indexList)[0]).(*intPair)
startIndex = v.a
endIndex = v.b
if startIndex < 0 && startIndex >= -maxValue {
startIndex = maxValue + startIndex
}
if endIndex < 0 && endIndex >= -maxValue {
endIndex = maxValue + endIndex + 1
}
if startIndex < 0 || startIndex > maxValue {
err = indexTerm.Errorf("range start-index %d is out of bounds", startIndex)
} else if endIndex < 0 || endIndex > maxValue {
err = indexTerm.Errorf("range end-index %d is out of bounds", endIndex)
} else if startIndex > endIndex {
err = indexTerm.Errorf("range start-index %d must not be greater than end-index %d", startIndex, endIndex)
}
return
}
func evalIndex(ctx ExprContext, self *term) (v any, err error) {
var leftValue, rightValue any
var indexList *ListType
var ok bool
if err = self.checkOperands(); err != nil {
return
}
// if err = self.checkOperands(); err != nil {
// return
// }
if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
return
}
indexTerm := self.children[1]
if indexList, ok = rightValue.(*ListType); !ok {
err = self.Errorf("invalid index expression")
return
} else if len(*indexList) != 1 {
err = indexTerm.Errorf("one index only is allowed")
return
}
indexTerm := self.children[1]
switch unboxedValue := leftValue.(type) {
case *ListType:
var index int
if index, err = verifyIndex(indexTerm, indexList, len(*unboxedValue)); err == nil {
v = (*unboxedValue)[index]
}
case string:
var index int
if index, err = verifyIndex(indexTerm, indexList, len(unboxedValue)); err == nil {
v = string(unboxedValue[index])
}
case *DictType:
var ok bool
var indexValue any
if indexValue, err = verifyKey(indexTerm, indexList); err == nil {
if v, ok = (*unboxedValue)[indexValue]; !ok {
err = indexTerm.Errorf("key %v does not belong to the dictionary", rightValue)
if IsInteger((*indexList)[0]) {
switch unboxedValue := leftValue.(type) {
case *ListType:
var index int
if index, err = verifyIndex(indexTerm, indexList, len(*unboxedValue)); err == nil {
v = (*unboxedValue)[index]
}
case string:
var index int
if index, err = verifyIndex(indexTerm, indexList, len(unboxedValue)); err == nil {
v = string(unboxedValue[index])
}
case *DictType:
var ok bool
var indexValue any
if indexValue, err = verifyKey(indexTerm, indexList); err == nil {
if v, ok = (*unboxedValue)[indexValue]; !ok {
err = indexTerm.Errorf("key %v does not belong to the dictionary", rightValue)
}
}
default:
err = self.errIncompatibleTypes(leftValue, rightValue)
}
} else if isIntPair((*indexList)[0]) {
switch unboxedValue := leftValue.(type) {
case *ListType:
var start, end int
if start, end, err = verifyRange(indexTerm, indexList, len(*unboxedValue)); err == nil {
sublist := ListType((*unboxedValue)[start:end])
v = &sublist
}
case string:
var start, end int
if start, end, err = verifyRange(indexTerm, indexList, len(unboxedValue)); err == nil {
v = unboxedValue[start:end]
}
default:
err = self.errIncompatibleTypes(leftValue, rightValue)
}
default:
err = self.errIncompatibleTypes(leftValue, rightValue)
}
return
}