From 5ec8d0d6230ad7e8a98db8f17b625448226c4837 Mon Sep 17 00:00:00 2001
From: Zahary Karadjov <zahary@gmail.com>
Date: Fri, 13 May 2022 14:43:34 +0300
Subject: [PATCH] wip

---
 confutils/cli_parser.nim | 58 ++++++++++++++++++++++++++++++++++++++++
 confutils/defs.nim       |  8 +++---
 2 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/confutils/cli_parser.nim b/confutils/cli_parser.nim
index 0cf2a99..f5554ae 100644
--- a/confutils/cli_parser.nim
+++ b/confutils/cli_parser.nim
@@ -8,6 +8,11 @@ type
     cmdLongOption,            ## A long option such as --option
     cmdShortOption            ## A short option such as -c
 
+  TriBool* = enum
+    Yes,
+    No,
+    Maybe
+
   OptParser* = object of RootObj ## Implementation of the command line parser.
     pos*: int
     inShortState: bool
@@ -21,6 +26,59 @@ type
                               ## or the argument, and the value is not "" if
                               ## the option was given a value
 
+type
+  FieldReader*[ConfigType] = proc (conf: var ConfigType, val: TaintedString)
+                                  {.gcsafe, raises: [Defect, CatchableError].}
+
+  Transition = object
+    nextState: uint16
+    fieldReaderState: FieldReaderState
+
+  CliDFA*[ConfigType] = object
+    flagNames: Table[string, int] # TODO replace this with perfect hashing
+    
+    fieldReaders: seq[FieldReader[configType]]
+      ## 
+
+    FieldReaderState = distinct uint16
+      # 15 bits for the field reader index
+      # 1 bits to determine the type of the field reader (optional or not)
+      # The special value `noFieldReader` indicates that there is no
+      # current field Reader
+
+    numStates: int
+
+    stateTransitions: seq[Transition]
+      ## You can think of this as a two dimentional array where we specify
+      ## how each flag index is handled in each state.
+      ##
+      ## The flags that are invalid in a particular state are marked with
+      ## the `invalidTransition` value. Otherwise, the transition indicates
+      ## how the state
+    
+  CliParserState = object
+    currentState: uint16
+    fieldReaderState: FieldReaderState
+
+const 
+  fieldNotExpected* = FieldReaderState max(uint16)
+  invalidTransition* = Transition(nextState: -1, fieldReaderState: fieldNotExpected)
+  
+template isFieldExpected(stateParam: FieldReaderState): TriBool =
+  let state = uint16(stateParam)
+  if state == uint16(fieldNotExpected):
+    No
+  elif (state and 1) != 0:
+    Yes:
+  else:
+    Maybe
+
+template readerIdx(state: FieldReaderState) =
+  uint16(state) shr 1
+
+template init(T: type FieldReaderState, idx: uint16, valueOptional: bool): T =
+  T((idx shl 1) or uint16(valueOptional))
+
 proc parseWord(s: string, i: int, w: var string,
                delim: set[char] = {'\t', ' '}): int =
   result = i
diff --git a/confutils/defs.nim b/confutils/defs.nim
index ab5d808..b4529cc 100644
--- a/confutils/defs.nim
+++ b/confutils/defs.nim
@@ -17,9 +17,6 @@ type
   OutDir* = distinct string
   OutFile* = distinct string
 
-  RestOfCmdLine* = distinct string
-  SubCommandArgs* = distinct string
-
   Flag* = object
     name*: TaintedString
 
@@ -46,16 +43,17 @@ template desc*(v: string) {.pragma.}
 template longDesc*(v: string) {.pragma.}
 template name*(v: string) {.pragma.}
 template abbr*(v: string) {.pragma.}
-template separator*(v: string) {.pragma.}
 template defaultValue*(v: untyped) {.pragma.}
 template defaultValueDesc*(v: string) {.pragma.}
+template separator*(v: string) {.pragma.}
 template required* {.pragma.}
 template command* {.pragma.}
 template argument* {.pragma.}
+template arguments* {.pragma.}
 template hidden* {.pragma.}
 template ignore* {.pragma.}
 template inlineConfiguration* {.pragma.}
-
+template forwardedCmdArgs*(separator: string = "--")* {.pragma.}
 template implicitlySelectable* {.pragma.}
   ## This can be applied to a case object discriminator
   ## to allow the value of the discriminator to be determined