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#
#
# Nim's Runtime Library
# (c) Copyright 2015 Dominik Picheta
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements nice syntactic sugar based on Nim's
## macro system.
import macros
proc createProcType(p, b: NimNode): NimNode {.compileTime.} =
#echo treeRepr(p)
#echo treeRepr(b)
result = newNimNode(nnkProcTy)
var formalParams = newNimNode(nnkFormalParams)
formalParams.add b
case p.kind
of nnkPar, nnkTupleConstr:
for i in 0 ..< p.len:
let ident = p[i]
var identDefs = newNimNode(nnkIdentDefs)
case ident.kind
of nnkExprColonExpr:
identDefs.add ident[0]
identDefs.add ident[1]
else:
identDefs.add newIdentNode("i" & $i)
identDefs.add(ident)
identDefs.add newEmptyNode()
formalParams.add identDefs
else:
var identDefs = newNimNode(nnkIdentDefs)
identDefs.add newIdentNode("i0")
identDefs.add(p)
identDefs.add newEmptyNode()
formalParams.add identDefs
result.add formalParams
result.add newEmptyNode()
#echo(treeRepr(result))
#echo(result.toStrLit())
macro `=>`*(p, b: untyped): untyped =
## Syntax sugar for anonymous procedures.
##
## .. code-block:: nim
##
## proc passTwoAndTwo(f: (int, int) -> int): int =
## f(2, 2)
##
## passTwoAndTwo((x, y) => x + y) # 4
#echo treeRepr(p)
#echo(treeRepr(b))
var params: seq[NimNode] = @[newIdentNode("auto")]
case p.kind
of nnkPar, nnkTupleConstr:
for c in children(p):
var identDefs = newNimNode(nnkIdentDefs)
case c.kind
of nnkExprColonExpr:
identDefs.add(c[0])
identDefs.add(c[1])
identDefs.add(newEmptyNode())
of nnkIdent:
identDefs.add(c)
identDefs.add(newIdentNode("auto"))
identDefs.add(newEmptyNode())
of nnkInfix:
if c[0].kind == nnkIdent and c[0].ident == !"->":
var procTy = createProcType(c[1], c[2])
params[0] = procTy[0][0]
for i in 1 ..< procTy[0].len:
params.add(procTy[0][i])
else:
error("Expected proc type (->) got (" & $c[0].ident & ").")
break
else:
echo treeRepr c
error("Incorrect procedure parameter list.")
params.add(identDefs)
of nnkIdent:
var identDefs = newNimNode(nnkIdentDefs)
identDefs.add(p)
identDefs.add(newIdentNode("auto"))
identDefs.add(newEmptyNode())
params.add(identDefs)
of nnkInfix:
if p[0].kind == nnkIdent and p[0].ident == !"->":
var procTy = createProcType(p[1], p[2])
params[0] = procTy[0][0]
for i in 1 ..< procTy[0].len:
params.add(procTy[0][i])
else:
error("Expected proc type (->) got (" & $p[0].ident & ").")
else:
error("Incorrect procedure parameter list.")
result = newProc(params = params, body = b, procType = nnkLambda)
#echo(result.treeRepr)
#echo(result.toStrLit())
#return result # TODO: Bug?
macro `->`*(p, b: untyped): untyped =
## Syntax sugar for procedure types.
##
## .. code-block:: nim
##
## proc pass2(f: (float, float) -> float): float =
## f(2, 2)
##
## # is the same as:
##
## proc pass2(f: proc (x, y: float): float): float =
## f(2, 2)
result = createProcType(p, b)
type ListComprehension = object
var lc* {.deprecated.}: ListComprehension
template `|`*(lc: ListComprehension, comp: untyped): untyped {.deprecated.} = lc
macro `[]`*(lc: ListComprehension, comp, typ: untyped): untyped {.deprecated.} =
## List comprehension, returns a sequence. `comp` is the actual list
## comprehension, for example ``x | (x <- 1..10, x mod 2 == 0)``. `typ` is
## the type that will be stored inside the result seq.
##
## .. code-block:: nim
##
## echo lc[x | (x <- 1..10, x mod 2 == 0), int]
##
## const n = 20
## echo lc[(x,y,z) | (x <- 1..n, y <- x..n, z <- y..n, x*x + y*y == z*z),
## tuple[a,b,c: int]]
## **Deprecated since version 0.19.9**
expectLen(comp, 3)
expectKind(comp, nnkInfix)
assert($comp[0] == "|")
result = newCall(
newDotExpr(
newIdentNode("result"),
newIdentNode("add")),
comp[1])
for i in countdown(comp[2].len-1, 0):
let x = comp[2][i]
expectMinLen(x, 1)
if x[0].kind == nnkIdent and $x[0].ident == "<-":
expectLen(x, 3)
result = newNimNode(nnkForStmt).add(x[1], x[2], result)
else:
result = newIfStmt((x, result))
result = newNimNode(nnkCall).add(
newNimNode(nnkPar).add(
newNimNode(nnkLambda).add(
newEmptyNode(),
newEmptyNode(),
newEmptyNode(),
newNimNode(nnkFormalParams).add(
newNimNode(nnkBracketExpr).add(
newIdentNode("seq"),
typ)),
newEmptyNode(),
newEmptyNode(),
newStmtList(
newAssignment(
newIdentNode("result"),
newNimNode(nnkPrefix).add(
newIdentNode("@"),
newNimNode(nnkBracket))),
result))))
macro dump*(x: typed): untyped =
## Dumps the content of an expression, useful for debugging.
## It accepts any expression and prints a textual representation
## of the tree representing the expression - as it would appear in
## source code - together with the value of the expression.
##
## As an example,
##
## .. code-block:: nim
## let
## x = 10
## y = 20
## dump(x + y)
##
## will print ``x + y = 30``.
let s = x.toStrLit
let r = quote do:
debugEcho `s`, " = ", `x`
return r
# TODO: consider exporting this in macros.nim
proc freshIdentNodes(ast: NimNode): NimNode =
# Replace NimIdent and NimSym by a fresh ident node
# see also https://github.com/nim-lang/Nim/pull/8531#issuecomment-410436458
proc inspect(node: NimNode): NimNode =
case node.kind:
of nnkIdent, nnkSym:
result = ident($node)
of nnkEmpty, nnkLiterals:
result = node
else:
result = node.kind.newTree()
for child in node:
result.add inspect(child)
result = inspect(ast)
macro distinctBase*(T: typedesc): untyped =
## reverses ``type T = distinct A``; works recursively.
runnableExamples:
type T = distinct int
doAssert distinctBase(T) is int
doAssert: not compiles(distinctBase(int))
type T2 = distinct T
doAssert distinctBase(T2) is int
let typeNode = getTypeImpl(T)
expectKind(typeNode, nnkBracketExpr)
if typeNode[0].typeKind != ntyTypeDesc:
error "expected typeDesc, got " & $typeNode[0]
var typeSym = typeNode[1]
typeSym = getTypeImpl(typeSym)
if typeSym.typeKind != ntyDistinct:
error "type is not distinct"
typeSym = typeSym[0]
while typeSym.typeKind == ntyDistinct:
typeSym = getTypeImpl(typeSym)[0]
typeSym.freshIdentNodes
|