diff options
-rw-r--r-- | changelog.md | 2 | ||||
-rw-r--r-- | lib/core/macros.nim | 16 | ||||
-rw-r--r-- | tests/macros/tmacro1.nim | 14 |
3 files changed, 31 insertions, 1 deletions
diff --git a/changelog.md b/changelog.md index 1f2655d7a..9a5671757 100644 --- a/changelog.md +++ b/changelog.md @@ -25,6 +25,8 @@ - Added `split`, `splitWhitespace`, `size`, `alignLeft`, `align`, `strip`, `repeat` procs and iterators to `unicode.nim`. +- Added `or` for `NimNode` in `macros`. + ### Library changes diff --git a/lib/core/macros.nim b/lib/core/macros.nim index 2b0d74e6a..79195966e 100644 --- a/lib/core/macros.nim +++ b/lib/core/macros.nim @@ -176,6 +176,21 @@ proc `[]=`*(n: NimNode, i: BackwardsIndex, child: NimNode) = ## set `n`'s `i`'th child to `child`. n[n.len - i.int] = child +template `or`*(x, y: NimNode): NimNode = + ## Evaluate ``x`` and when it is not an empty node, return + ## it. Otherwise evaluate to ``y``. Can be used to chain several + ## expressions to get the first expression that is not empty. + ## + ## .. code-block:: nim + ## + ## let node = mightBeEmpty() or mightAlsoBeEmpty() or fallbackNode + + let arg = x + if arg != nil and arg.kind != nnkEmpty: + arg + else: + y + proc add*(father, child: NimNode): NimNode {.magic: "NAdd", discardable, noSideEffect, locks: 0.} ## Adds the `child` to the `father` node. Returns the @@ -1433,4 +1448,3 @@ proc getProjectPath*(): string = discard ## Returns the path to the currently compiling project, not to ## be confused with ``system.currentSourcePath`` which returns ## the path of the current module. - diff --git a/tests/macros/tmacro1.nim b/tests/macros/tmacro1.nim index ac2bf9094..5388e861c 100644 --- a/tests/macros/tmacro1.nim +++ b/tests/macros/tmacro1.nim @@ -79,3 +79,17 @@ static: assert fooSym.kind in {nnkOpenSymChoice, nnkClosedSymChoice} assert fooSym.eqIdent("fOO") assertNot fooSym.eqIdent("bar") + + var empty: NimNode + var myLit = newLit("str") + + assert( (empty or myLit) == myLit ) + + empty = newEmptyNode() + + assert( (empty or myLit) == myLit ) + + proc bottom(): NimNode = + quit("may not be evaluated") + + assert( (myLit or bottom()) == myLit ) |