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#
#
# Nimrod's Runtime Library
# (c) Copyright 2009 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements Nimrod's support for the ``variant`` datatype.
## `TVariant` shows how the flexibility of dynamic typing is achieved
## within a static type system.
type
TVarType* = enum
vtNone,
vtBool,
vtChar,
vtEnum,
vtInt,
vtFloat,
vtString,
vtSet,
vtSeq,
vtDict
TVariant* {.final.} = object of TObject
case vtype: TVarType
of vtNone: nil
of vtBool, vtChar, vtEnum, vtInt: vint: int64
of vtFloat: vfloat: float64
of vtString: vstring: string
of vtSet, vtSeq: q: seq[TVariant]
of vtDict: d: seq[tuple[key, val: TVariant]]
iterator objectFields*[T](x: T, skipInherited: bool): tuple[
key: string, val: TVariant] {.magic: "ObjectFields"}
proc `<>`*(x: ordinal): TVariant =
result.kind = vtEnum
result.vint = x
proc `<>`*(x: biggestInt): TVariant =
result.kind = vtInt
result.vint = x
proc `<>`*(x: char): TVariant =
result.kind = vtChar
result.vint = ord(x)
proc `<>`*(x: bool): TVariant =
result.kind = vtBool
result.vint = ord(x)
proc `<>`*(x: biggestFloat): TVariant =
result.kind = vtFloat
result.vfloat = x
proc `<>`*(x: string): TVariant =
result.kind = vtString
result.vstring = x
proc `<>`*[T](x: openArray[T]): TVariant =
result.kind = vtSeq
newSeq(result.q, x.len)
for i in 0..x.len-1: result.q[i] = <>x[i]
proc `<>`*[T](x: set[T]): TVariant =
result.kind = vtSet
result.q = @[]
for a in items(x): result.q.add(<>a)
proc `<>`* [T: object](x: T): TVariant {.magic: "ToVariant".}
## this converts a value to a variant ("boxing")
proc `><`*[T](v: TVariant, typ: T): T {.magic: "FromVariant".}
[<>5, <>67, <>"hello"]
myVar><int
proc `==`* (x, y: TVariant): bool =
if x.vtype == y.vtype:
case x.vtype
of vtNone: result = true
of vtBool, vtChar, vtEnum, vtInt: result = x.vint == y.vint
of vtFloat: result = x.vfloat == y.vfloat
of vtString: result = x.vstring == y.vstring
of vtSet:
# complicated! We check that each a in x also occurs in y and that the
# counts are identical:
if x.q.len == y.q.len:
for a in items(x.q):
block inner:
for b in items(y.q):
if a == b: break inner
return false
result = true
of vtSeq:
if x.q.len == y.q.len:
for i in 0..x.q.len-1:
if x.q[i] != y.q[i]: return false
result = true
of vtDict:
# it is an ordered dict:
if x.d.len == y.d.len:
for i in 0..x.d.len-1:
if x.d[i].key != y.d[i].key: return false
if x.d[i].val != y.d[i].val: return false
result = true
proc `[]`* (a, b: TVariant): TVariant =
case a.vtype
of vtSeq:
if b.vtype in {vtBool, vtChar, vtEnum, vtInt}:
result = a.q[b.vint]
else:
variantError()
of vtDict:
for i in 0..a.d.len-1:
if a.d[i].key == b: return a.d[i].val
if b.vtype in {vtBool, vtChar, vtEnum, vtInt}:
result = a.d[b.vint].val
variantError()
else: variantError()
proc `[]=`* (a, b, c: TVariant) =
case a.vtype
of vtSeq:
if b.vtype in {vtBool, vtChar, vtEnum, vtInt}:
a.q[b.vint] = b
else:
variantError()
of vtDict:
for i in 0..a.d.len-1:
if a.d[i].key == b:
a.d[i].val = c
return
if b.vtype in {vtBool, vtChar, vtEnum, vtInt}:
a.d[b.vint].val = c
variantError()
else: variantError()
proc `[]`* (a: TVariant, b: int): TVariant {.inline} = return a[<>b]
proc `[]`* (a: TVariant, b: string): TVariant {.inline} = return a[<>b]
proc `[]=`* (a: TVariant, b: int, c: TVariant) {.inline} = a[<>b] = c
proc `[]=`* (a: TVariant, b: string, c: TVariant) {.inline} = a[<>b] = c
proc `+`* (x, y: TVariant): TVariant =
case x.vtype
of vtBool, vtChar, vtEnum, vtInt:
if y.vtype == x.vtype:
result.vtype = x.vtype
result.vint = x.vint + y.vint
else:
case y.vtype
of vtBool, vtChar, vtEnum, vtInt:
vint: int64
of vtFloat: vfloat: float64
of vtString: vstring: string
of vtSet, vtSeq: q: seq[TVariant]
of vtDict: d: seq[tuple[key, val: TVariant]]
proc `-`* (x, y: TVariant): TVariant
proc `*`* (x, y: TVariant): TVariant
proc `/`* (x, y: TVariant): TVariant
proc `div`* (x, y: TVariant): TVariant
proc `mod`* (x, y: TVariant): TVariant
proc `&`* (x, y: TVariant): TVariant
proc `$`* (x: TVariant): string =
# uses JS notation
proc parseVariant*(s: string): TVariant
proc `<`* (x, y: TVariant): bool
proc `<=`* (x, y: TVariant): bool
proc hash*(x: TVariant): int =
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