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low/high/of are now overloadable operations
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@Araq
Araq committed Aug 30, 2017
1 parent 786f931 commit 8d714d2
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Showing 3 changed files with 64 additions and 56 deletions.
41 changes: 3 additions & 38 deletions compiler/semexprs.nim
View file
Expand Up @@ -274,41 +274,6 @@ proc semSizeof(c: PContext, n: PNode): PNode =
n.typ = getSysType(tyInt)
result = n

proc semOf(c: PContext, n: PNode): PNode =
if sonsLen(n) == 3:
n.sons[1] = semExprWithType(c, n.sons[1])
n.sons[2] = semExprWithType(c, n.sons[2], {efDetermineType})
#restoreOldStyleType(n.sons[1])
#restoreOldStyleType(n.sons[2])
let a = skipTypes(n.sons[1].typ, abstractPtrs)
let b = skipTypes(n.sons[2].typ, abstractPtrs)
let x = skipTypes(n.sons[1].typ, abstractPtrs-{tyTypeDesc})
let y = skipTypes(n.sons[2].typ, abstractPtrs-{tyTypeDesc})

if x.kind == tyTypeDesc or y.kind != tyTypeDesc:
localError(n.info, errXExpectsObjectTypes, "of")
elif b.kind != tyObject or a.kind != tyObject:
localError(n.info, errXExpectsObjectTypes, "of")
else:
let diff = inheritanceDiff(a, b)
# | returns: 0 iff `a` == `b`
# | returns: -x iff `a` is the x'th direct superclass of `b`
# | returns: +x iff `a` is the x'th direct subclass of `b`
# | returns: `maxint` iff `a` and `b` are not compatible at all
if diff <= 0:
# optimize to true:
message(n.info, hintConditionAlwaysTrue, renderTree(n))
result = newIntNode(nkIntLit, 1)
result.info = n.info
result.typ = getSysType(tyBool)
return result
elif diff == high(int):
localError(n.info, errXcanNeverBeOfThisSubtype, typeToString(a))
else:
localError(n.info, errXExpectsTwoArguments, "of")
n.typ = getSysType(tyBool)
result = n

proc isOpImpl(c: PContext, n: PNode, flags: TExprFlags): PNode =
internalAssert n.sonsLen == 3 and
n[1].typ != nil and n[1].typ.kind == tyTypeDesc and
Expand Down Expand Up @@ -1831,11 +1796,11 @@ proc semMagic(c: PContext, n: PNode, s: PSym, flags: TExprFlags): PNode =
of mDefined: result = semDefined(c, setMs(n, s), false)
of mDefinedInScope: result = semDefined(c, setMs(n, s), true)
of mCompiles: result = semCompiles(c, setMs(n, s), flags)
of mLow: result = semLowHigh(c, setMs(n, s), mLow)
of mHigh: result = semLowHigh(c, setMs(n, s), mHigh)
#of mLow: result = semLowHigh(c, setMs(n, s), mLow)
#of mHigh: result = semLowHigh(c, setMs(n, s), mHigh)
of mSizeOf: result = semSizeof(c, setMs(n, s))
of mIs: result = semIs(c, setMs(n, s), flags)
of mOf: result = semOf(c, setMs(n, s))
#of mOf: result = semOf(c, setMs(n, s))
of mShallowCopy: result = semShallowCopy(c, n, flags)
of mExpandToAst: result = semExpandToAst(c, n, s, flags)
of mQuoteAst: result = semQuoteAst(c, n)
Expand Down
36 changes: 36 additions & 0 deletions compiler/semmagic.nim
View file
Expand Up @@ -200,6 +200,41 @@ proc isStrangeArray(t: PType): bool =
let t = t.skipTypes(abstractInst)
result = t.kind == tyArray and t.firstOrd != 0

proc semOf(c: PContext, n: PNode): PNode =
if sonsLen(n) == 3:
n.sons[1] = semExprWithType(c, n.sons[1])
n.sons[2] = semExprWithType(c, n.sons[2], {efDetermineType})
#restoreOldStyleType(n.sons[1])
#restoreOldStyleType(n.sons[2])
let a = skipTypes(n.sons[1].typ, abstractPtrs)
let b = skipTypes(n.sons[2].typ, abstractPtrs)
let x = skipTypes(n.sons[1].typ, abstractPtrs-{tyTypeDesc})
let y = skipTypes(n.sons[2].typ, abstractPtrs-{tyTypeDesc})

if x.kind == tyTypeDesc or y.kind != tyTypeDesc:
localError(n.info, errXExpectsObjectTypes, "of")
elif b.kind != tyObject or a.kind != tyObject:
localError(n.info, errXExpectsObjectTypes, "of")
else:
let diff = inheritanceDiff(a, b)
# | returns: 0 iff `a` == `b`
# | returns: -x iff `a` is the x'th direct superclass of `b`
# | returns: +x iff `a` is the x'th direct subclass of `b`
# | returns: `maxint` iff `a` and `b` are not compatible at all
if diff <= 0:
# optimize to true:
message(n.info, hintConditionAlwaysTrue, renderTree(n))
result = newIntNode(nkIntLit, 1)
result.info = n.info
result.typ = getSysType(tyBool)
return result
elif diff == high(int):
localError(n.info, errXcanNeverBeOfThisSubtype, typeToString(a))
else:
localError(n.info, errXExpectsTwoArguments, "of")
n.typ = getSysType(tyBool)
result = n

proc magicsAfterOverloadResolution(c: PContext, n: PNode,
flags: TExprFlags): PNode =
case n[0].sym.magic
Expand All @@ -219,6 +254,7 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
result.typ = getSysType(tyString)
of mInstantiationInfo: result = semInstantiationInfo(c, n)
of mOrd: result = semOrd(c, n)
of mOf: result = semOf(c, n)
of mHigh, mLow: result = semLowHigh(c, n, n[0].sym.magic)
of mShallowCopy: result = semShallowCopy(c, n, flags)
of mNBindSym: result = semBindSym(c, n)
Expand Down
43 changes: 25 additions & 18 deletions lib/system.nim
View file
Expand Up @@ -231,9 +231,22 @@ proc reset*[T](obj: var T) {.magic: "Reset", noSideEffect.}
## resets an object `obj` to its initial (binary zero) value. This needs to
## be called before any possible `object branch transition`:idx:.

# for low and high the return type T may not be correct, but
# we handle that with compiler magic in semLowHigh()
proc high*[T](x: T): T {.magic: "High", noSideEffect.}
type
range*{.magic: "Range".}[T] ## Generic type to construct range types.
array*{.magic: "Array".}[I, T] ## Generic type to construct
## fixed-length arrays.
openArray*{.magic: "OpenArray".}[T] ## Generic type to construct open arrays.
## Open arrays are implemented as a
## pointer to the array data and a
## length field.
varargs*{.magic: "Varargs".}[T] ## Generic type to construct a varargs type.
seq*{.magic: "Seq".}[T] ## Generic type to construct sequences.
set*{.magic: "Set".}[T] ## Generic type to construct bit sets.

UncheckedArray* {.unchecked.}[T] = array[0, T]
## Array with no bounds checking

proc high*[T: Ordinal](x: T): T {.magic: "High", noSideEffect.}
## returns the highest possible index of an array, a sequence, a string or
## the highest possible value of an ordinal value `x`. As a special
## semantic rule, `x` may also be a type identifier.
Expand All @@ -245,6 +258,13 @@ proc high*[T](x: T): T {.magic: "High", noSideEffect.}
## high(2) #=> 9223372036854775807
## high(int) #=> 9223372036854775807

proc high*[T: Ordinal](x: typeDesc[T]): T {.magic: "High", noSideEffect.}
proc high*[T](x: openArray[T]): int {.magic: "High", noSideEffect.}
proc high*[I, T](x: array[I, T]): I {.magic: "High", noSideEffect.}

proc low*[T: Ordinal](x: typeDesc[T]): T {.magic: "Low", noSideEffect.}
proc low*[T](x: openArray[T]): int {.magic: "Low", noSideEffect.}
proc low*[I, T](x: array[I, T]): I {.magic: "Low", noSideEffect.}
proc low*[T](x: T): T {.magic: "Low", noSideEffect.}
## returns the lowest possible index of an array, a sequence, a string or
## the lowest possible value of an ordinal value `x`. As a special
Expand All @@ -256,21 +276,6 @@ proc low*[T](x: T): T {.magic: "Low", noSideEffect.}
## low(2) #=> -9223372036854775808
## low(int) #=> -9223372036854775808

type
range*{.magic: "Range".}[T] ## Generic type to construct range types.
array*{.magic: "Array".}[I, T] ## Generic type to construct
## fixed-length arrays.
openArray*{.magic: "OpenArray".}[T] ## Generic type to construct open arrays.
## Open arrays are implemented as a
## pointer to the array data and a
## length field.
varargs*{.magic: "Varargs".}[T] ## Generic type to construct a varargs type.
seq*{.magic: "Seq".}[T] ## Generic type to construct sequences.
set*{.magic: "Set".}[T] ## Generic type to construct bit sets.

UncheckedArray* {.unchecked.}[T] = array[0, T]
## Array with no bounds checking

when defined(nimArrIdx):
# :array|openarray|string|seq|cstring|tuple
proc `[]`*[I: Ordinal;T](a: T; i: I): T {.
Expand Down Expand Up @@ -1175,6 +1180,8 @@ proc `is` *[T, S](x: T, y: S): bool {.magic: "Is", noSideEffect.}
template `isnot` *(x, y: untyped): untyped = not (x is y)
## Negated version of `is`. Equivalent to ``not(x is y)``.

proc `of` *[T, S](x: typeDesc[T], y: typeDesc[S]): bool {.magic: "Of", noSideEffect.}
proc `of` *[T, S](x: T, y: typeDesc[S]): bool {.magic: "Of", noSideEffect.}
proc `of` *[T, S](x: T, y: S): bool {.magic: "Of", noSideEffect.}
## Checks if `x` has a type of `y`
##
Expand Down

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