From c86dac32d38cf2be5faa6118911429a231de8805 Mon Sep 17 00:00:00 2001
From: kitsunyan
Date: Sun, 26 Apr 2020 08:14:06 +0300
Subject: Backport list comprehension

---
 src/args.nim                |  2 +-
 src/aur.nim                 |  2 +-
 src/common.nim              |  2 +-
 src/feature/syncinfo.nim    |  2 +-
 src/feature/syncinstall.nim |  2 +-
 src/format.nim              |  2 +-
 src/lc.nim                  | 30 ++++++++++++++++++++++++++++++
 src/main.nim                |  2 +-
 src/package.nim             |  3 ++-
 src/pacman.nim              |  2 +-
 10 files changed, 40 insertions(+), 9 deletions(-)
 create mode 100644 src/lc.nim

diff --git a/src/args.nim b/src/args.nim
index fd03ee0..87fbaf3 100644
--- a/src/args.nim
+++ b/src/args.nim
@@ -1,6 +1,6 @@
 import
   options, os, posix, sequtils, sets, strutils, sugar,
-  utils
+  lc, utils
 
 type
   ArgumentType* {.pure.} = enum
diff --git a/src/aur.nim b/src/aur.nim
index 399183c..cd1c744 100644
--- a/src/aur.nim
+++ b/src/aur.nim
@@ -1,6 +1,6 @@
 import
   json, lists, options, re, sequtils, sets, strutils, sugar, tables,
-  package, utils,
+  lc, package, utils,
   "wrapper/curl"
 
 type
diff --git a/src/common.nim b/src/common.nim
index 8db3a79..3f9013c 100644
--- a/src/common.nim
+++ b/src/common.nim
@@ -1,6 +1,6 @@
 import
   options, os, osproc, posix, sequtils, sets, strutils, sugar, tables,
-  args, config, format, lists, package, pacman, utils,
+  args, config, format, lc, lists, package, pacman, utils,
   "wrapper/alpm"
 
 type
diff --git a/src/feature/syncinfo.nim b/src/feature/syncinfo.nim
index 4f758fe..f4c6f7a 100644
--- a/src/feature/syncinfo.nim
+++ b/src/feature/syncinfo.nim
@@ -1,6 +1,6 @@
 import
   options, posix, sequtils, strutils, sugar, tables,
-  "../args", "../aur", "../common", "../config", "../format", "../package",
+  "../args", "../aur", "../common", "../config", "../format", "../lc", "../package",
     "../pacman", "../utils",
   "../wrapper/alpm"
 
diff --git a/src/feature/syncinstall.nim b/src/feature/syncinstall.nim
index 7aba043..0a9170d 100644
--- a/src/feature/syncinstall.nim
+++ b/src/feature/syncinstall.nim
@@ -1,6 +1,6 @@
 import
   algorithm, options, os, posix, sequtils, sets, strutils, sugar, tables,
-  "../args", "../aur", "../config", "../common", "../format", "../lists", "../package",
+  "../args", "../aur", "../config", "../common", "../format", "../lc", "../lists", "../package",
     "../pacman", "../utils",
   "../wrapper/alpm"
 
diff --git a/src/format.nim b/src/format.nim
index 2ac39dc..e8645b8 100644
--- a/src/format.nim
+++ b/src/format.nim
@@ -1,6 +1,6 @@
 import
   macros, options, posix, sequtils, strutils, sugar, times, unicode,
-  utils
+  lc, utils
 
 type
   PackageLineFormat* = tuple[
diff --git a/src/lc.nim b/src/lc.nim
new file mode 100644
index 0000000..0e75d28
--- /dev/null
+++ b/src/lc.nim
@@ -0,0 +1,30 @@
+import macros
+
+# backported list comprehension from earlier nim versions
+
+type ListComprehension = object
+var lc*: ListComprehension
+
+template `|`*(lc: ListComprehension, comp: untyped): untyped = lc
+
+macro `[]`*(lc: ListComprehension, comp, typ: untyped): untyped =
+  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].strVal == "<-":
+      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))))
diff --git a/src/main.nim b/src/main.nim
index 92e8887..f815f8f 100644
--- a/src/main.nim
+++ b/src/main.nim
@@ -1,6 +1,6 @@
 import
   options, os, posix, re, sequtils, strutils, sugar,
-  args, config, format, pacman, utils
+  args, config, format, lc, pacman, utils
 
 import
   "feature/localquery",
diff --git a/src/package.nim b/src/package.nim
index 5b87184..b4153db 100644
--- a/src/package.nim
+++ b/src/package.nim
@@ -1,5 +1,6 @@
 import
-  options, os, re, sequtils, sets, strutils, sugar, tables, utils,
+  options, os, re, sequtils, sets, strutils, sugar, tables,
+  lc, utils,
   "wrapper/alpm"
 
 type
diff --git a/src/pacman.nim b/src/pacman.nim
index 857581f..5766ee2 100644
--- a/src/pacman.nim
+++ b/src/pacman.nim
@@ -1,6 +1,6 @@
 import
   macros, options, posix, sequtils, sets, strutils, sugar, tables,
-  args, config, utils
+  args, config, lc, utils
 
 type
   OpGroup* {.pure.} = enum
-- 
cgit v1.2.3-70-g09d2