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_.length and _.lastindex for arrays

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Karol Stasiak
2019-07-29 22:50:26 +02:00
parent 5fb6efbd61
commit dd4cb17a80
2 changed files with 31 additions and 0 deletions
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13
docs/lang/syntax.md
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@@ -149,6 +149,19 @@ If the declared size and the size deduced from the `<initial_values>` don't matc
* `<initial_values>` is an array literal, see [Literals](./literals.md). * `<initial_values>` is an array literal, see [Literals](./literals.md).
Local arrays can have initial values only if they're const. Local arrays can have initial values only if they're const.
Each array has an associated constant defined that contains its length
and, if the indices are numeric, another constant that contains the last index of the array:
array x[5]
x.length // equals 5
x.lastindex // equals 4
enum e { ... }
array y[e]
y.length // equals e.count
// y.lastindex // doesn't exist
TODO TODO
### Function declarations ### Function declarations

18
src/main/scala/millfork/env/Environment.scala vendored
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@@ -1458,6 +1458,15 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
} }
if (length < 256) { if (length < 256) {
addThing(ConstantThing(arrayName + ".length", lengthConst, b), stmt.position) addThing(ConstantThing(arrayName + ".length", lengthConst, b), stmt.position)
} else {
addThing(ConstantThing(arrayName + ".length", lengthConst, w), stmt.position)
}
if (length > 0 && indexType.isArithmetic) {
if (length <= 256) {
addThing(ConstantThing(arrayName + ".lastindex", NumericConstant(length - 1, 1), b), stmt.position)
} else {
addThing(ConstantThing(arrayName + ".lastindex", NumericConstant(length - 1, 2), w), stmt.position)
}
} }
case _ => log.error(s"Array `${stmt.name}` has weird length", stmt.position) case _ => log.error(s"Array `${stmt.name}` has weird length", stmt.position)
} }
@@ -1531,6 +1540,15 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
} }
if (length < 256) { if (length < 256) {
addThing(ConstantThing(arrayName + ".length", NumericConstant(length, 1), b), stmt.position) addThing(ConstantThing(arrayName + ".length", NumericConstant(length, 1), b), stmt.position)
} else {
addThing(ConstantThing(arrayName + ".length", NumericConstant(length, 2), w), stmt.position)
}
if (length > 0 && indexType.isArithmetic) {
if (length <= 256) {
addThing(ConstantThing(arrayName + ".lastindex", NumericConstant(length - 1, 1), b), stmt.position)
} else {
addThing(ConstantThing(arrayName + ".lastindex", NumericConstant(length - 1, 2), w), stmt.position)
}
} }
} }
} }