From 0d19b846f2174139960772f3b08cc2fa00e95220 Mon Sep 17 00:00:00 2001
From: Florian Schroedl <flo.schroedl@gmail.com>
Date: Thu, 20 Jan 2022 17:00:00 +0100
Subject: [PATCH] Headline parser setup

---
 src/nim_org_parse.nim | 80 ++++++++++++++++++++++++++++++++++++++++++-
 src/utils/fp.nim      | 20 +++++++++++
 2 files changed, 99 insertions(+), 1 deletion(-)
 create mode 100644 src/utils/fp.nim

diff --git a/src/nim_org_parse.nim b/src/nim_org_parse.nim
index b5b6a5a..57f56b4 100644
--- a/src/nim_org_parse.nim
+++ b/src/nim_org_parse.nim
@@ -1 +1,79 @@
-echo "Hello World"
+import std/strutils
+import std/re
+import std/parseutils
+import std/strformat
+import std/sugar
+import fusion/matching
+import fp/maybe
+import fp/list
+import utils/fp
+
+{.experimental: "caseStmtMacros".}
+
+type contentT = string
+type headlingLevelT = int
+
+type lineNumberT = int
+type lineCharT = int
+type posT = (lineNumberT, lineCharT)
+
+type
+  OrgBlockKind* = enum
+    Document,
+    Heading,
+    NotImplemented
+  OrgBlock* = ref object
+    # position: posT
+    case kind*: OrgBlockKind
+    of Heading:
+      content*: contentT
+      level*: headlingLevelT
+    else: str: string
+
+proc `$`*(x: OrgBlock): string =
+  case x:
+    of Document():
+       return &"""OrgBlock(
+    kind: Document,
+)"""
+    of Heading(content: @content, level: @level):
+       return &"""OrgBlock(
+    kind: Heading,
+    content: {content},
+    level: {level},
+)"""
+    of NotImplemented(str: @str):
+       return &"""OrgBlock(
+    kind: NotImplemented,
+    str: {str},
+)"""
+
+proc parseHeadline(line: string): Maybe[OrgBlock] =
+  if line.startsWith("*"):
+    var token: string
+    let idx = line.parseWhile(token, validChars = { '*' })
+    # Eat the first space character
+    let content = line[idx + 1 .. ^1]
+
+    Just(OrgBlock(
+      kind: Heading,
+      level: idx,
+      content: content,
+    ))
+  else:
+    Nothing[OrgBlock]()
+
+let parsers = @[
+  parseHeadline,
+]
+
+proc parseLine(line: string): any =
+  parsers
+  .findMaybeFn(line)
+  # .fold(
+  #   () => OrgBlock(kind: NotImplemented, str: line),
+  #   x => x.get(),
+  # )
+
+
+echo parseLine("**** foo :bar:")
diff --git a/src/utils/fp.nim b/src/utils/fp.nim
new file mode 100644
index 0000000..7962040
--- /dev/null
+++ b/src/utils/fp.nim
@@ -0,0 +1,20 @@
+import std/sugar
+import fp/maybe
+
+proc findMaybe*[T](xs: seq[T], fn: T -> bool): Maybe[T] =
+  for x in xs:
+    if fn(x):
+      return Just(x)
+  return Nothing[T]()
+
+proc findMaybeFn*[T, B](fns: seq[T {.nimcall.} -> Maybe[B]], val: T): Maybe[B] =
+  for fn in fns:
+    let res = fn(val)
+    if res.isDefined():
+      return res
+  return Nothing[B]()
+
+when isMainModule:
+  echo @[
+  (x: int) => (if x == 2: Just("foo") else: Nothing[string]()),
+  ].findMaybeFn(2)