YALR (Yet Another Lexer Refactor)

lang/demo/single_toks.no

@@ -0,0 +1,2 @@
+[a]b(#)
+(c)d[e]

src/ddemo

@@ -1,3 +1,11 @@
 #!/usr/bin/env bash
+set -e
+
+if [ -z "$1" ]; then
+  echo "Usage: ddemo DEMOFILE"
+  echo "Demo files are located in lang/demo"
+  exit 1
+fi
+
 nim c nlx.nim
 ./nlx ../lang/demo/$1

src/nlx.nim

@@ -1,22 +1,19 @@
 import os
-import noether/lexer/tok
-import noether/lexer/tokstream
-import noether/parser/parser
+import noether/lib/io
+import noether/lexer/[tok, tokstream]
+# import noether/parser/parser
 
 {.hint: "Don't forget to drink more water (^_^)".}
 when isMainModule:
   echo "Noether Lang Extras v0.1.0 - nlx"
 
-  if paramCount() > 0:
-    let filename = paramStr(1)
-    var tokStream = newTokStream(filename, isFile=true)
+  var inStream = if paramCount() > 0: streamFile(paramStr 1)
+                 else: streamString(readAll stdin)
 
-    # # DumpTok
-    # while tokStream.progress():
-    #   echo tokStream.currTok
+  var stream = newTokStream(inStream)
+  # # DumpTok
+  while stream.progress():
+    echo stream.tok
 
-    # DumpTree
-    discard parse(tokStream)
-    
-  else:
-    echo "usage: nlx filename"
+  # DumpTree
+  # discard parse(tokStream)

src/noether/lexer/lstream.nim

@@ -1,66 +0,0 @@
-import std/streams
-import std/options
-
-import tok
-export tok
-
-type
-  # Character streaming for the nlTokStream
-  nlLStream = object
-    stream: Stream
-    # row/column positions
-    line*: string 
-    lineNum*: Natural
-    pos*: Natural
-
-proc streamFile*(filename: string): FileStream =
-  result = newFileStream(filename, fmRead)
-
-proc streamString*(str: string): StringStream =
-  result = newStringStream(str)
-
-proc newLStream*(content: string, isFile: bool = false): nlLStream =
-  result = nlLStream(
-    stream: if isFile: streamFile(content) else: streamString(content),
-    line: "",
-    lineNum: Natural 0,
-    pos: Natural 0,
-  )
-
-# Checks whether we've reached EOL
-# NOTE: also checks if we've surpassed it (ie invalid lstream.pos)
-proc atEOL*(lstream: nlLStream): bool = 
-  result = (lstream.pos >= lstream.line.len - 1)
-
-# Checks whether we are EXACTLY at EOL, but not surpassed
-proc exactlyEOL*(lstream: nlLStream): bool =
-  result = (lstream.pos == lstream.line.len - 1)
-
-# Checks whether we have surpassed EOL
-proc outOfBounds*(lstream: nlLStream): bool = 
-  result = (lstream.pos > lstream.line.len - 1)
-
-# Progress the lex stream to the next line (if available)
-proc progressLine*(lstream: var nlLStream): bool = 
-  if lstream.stream.readLine(lstream.line):
-    inc lstream.lineNum
-    lstream.pos = Natural 0
-    return true
-  return false
-
-# Progress the lex stream to the next character in the line
-# forcefully (aka does NOT check if we reached EOL)
-proc forceProgressChar*(lstream: var nlLStream) = 
-  inc lstream.pos
-
-# # Progress the lex stream to the next character (if available)
-# proc progressChar*(lstream: var nlLStream): bool =
-#   if not lstream.atEOL():
-#     lstream.forceProgressChar()
-#     result = true
-#   else:
-#     # attempt to progress next line past EOL
-#     result = lstream.progressLine()
-
-proc currChar*(lstream: nlLStream): char = 
-  result = lstream.line[lstream.pos]

src/noether/lexer/tok.nim

@@ -1,22 +1,25 @@
-include toktype
+include tokkind
 
 type 
-  nlTok* = object
-    tKind*: nlTokKind
-    lit*: string
-    lineNum*: Natural
-    startPos*: Natural
-    endPos*: Natural
+  nlTok* = tuple
+    # NOTE: nlTokBuilder will mutate nlTok.kind
+    kind: nlTokKind
+    lit: string
+    lineNum: int
+    startPos: int
+    endPos: int
 
 # Generates an "empty" nlTok with only a startPos,
 # all other fields are expected to be filled out later.
-proc emptyTok*(startPos: int): nlTok =
-  result = nlTok(
-    tKind: tkNONE,
+proc emptyTok*(startPos: int): nlTok {.inline.} =
+  result = (
+    kind: tkNONE,
     lit: "",
-    startPos: Natural startPos,
+    lineNum: 0,
+    startPos: startPos,
+    endPos: startPos,
   )
 
 # Checks if an nlTok has tkNONE
-proc isUntyped*(tKind: nlTokKind): bool =
-  result = (tKind == tkNONE)
+proc isUntyped*(tok: nlTok): bool {.inline.} =
+  result = (tok.kind == tkNONE)

src/noether/lexer/tokbuilder.nim

@@ -0,0 +1,123 @@
+import 
+  streams, 
+  options
+
+import tok
+export tok
+
+type
+  # Abstracts the "building process" (lexing) 
+  # of nlTok objects from a given Stream of characters.
+  nlTokBuilder* = object
+    stream: Stream
+    tok: nlTok # the build token
+    # track line number, line content, etc
+    line: string
+    lineNum: int
+    pos: int 
+    # save char and pos and its token type
+    char: char
+    cTKind: nlTokKind
+
+proc atEOL(builder: nlTokBuilder): bool {.inline.} =
+  result = (builder.char == '\n')
+proc atEOF(builder: nlTokBuilder): bool {.inline.} =
+  result = (builder.char == '\0')
+
+# Initialise a new token builder
+proc newBuilder(stream: var Stream): nlTokBuilder =
+  # NOTE: initial builder.char value is arbitrary, 
+  # NOTE: but CANNOT be initialised to the default '\0'
+  result = nlTokBuilder(
+    stream: stream,
+    tok: emptyTok(0),
+    line: "",
+    lineNum: 1,
+    pos: -1,    # after initial readChar this -> 0
+    char: '\0', # use \0 as initial invalid char   
+  )
+
+
+#[ ====================================================== ]
+ | nlTokBuilder Internal Interface for Token Construction ]
+ ]#
+  
+# Reset the build token to be "empty"
+proc resetBuild(builder: var nlTokBuilder) =
+  builder.tok = emptyTok(builder.pos)
+
+# "Finishes" the build token by setting various properties
+proc finishBuild(builder: var nlTokBuilder) =
+  builder.tok.lineNum = builder.lineNum
+  builder.tok.endPos = builder.pos
+  builder.tok.lit = builder.line[builder.tok.startPos ..< builder.line.high]
+
+# Finish, return, and reset the build token
+proc flushBuild(builder: var nlTokBuilder): nlTok = 
+  echo "Flush @", builder.pos
+  finishBuild(builder)
+  result = builder.tok
+  resetBuild(builder)
+
+# Is the build token "compatible" with the current char?
+# NOTE: flushBuild() is called if incompatible
+proc isCompatibleBuild(builder: nlTokBuilder): bool =
+  result = (builder.cTKind == builder.tok.kind)
+
+# Inherit the build token's type from current char
+proc inherit(builder: var nlTokBuilder) = 
+  builder.tok.kind = builder.cTKind
+
+# Add a character to the nlTokBuilder's build token.
+# Flushes and returns the build token if "fully built",
+# and a boolean indicating whether the nlTokBuilder can progress.
+proc appendBuild(builder: var nlTokBuilder, flushed: var Option[nlTok]): bool =    
+  # untyped build tokens inherit type immediately
+  if builder.tok.isUntyped():
+    builder.inherit()
+  
+  # check if EOF reached
+  # if builder.atEOL():
+  #     echo "EOL DETECT 1"
+  #     result = false # DO NOT PROGRESS
+  #     flushed = some(flushBuild(builder))
+  # check character and build token compatability
+  if not isCompatibleBuild(builder):
+      # flush old build token, the new one inherits type
+      flushed = some(flushBuild(builder))
+      builder.inherit()
+      result = true # can progress
+  else:
+    flushed = none(nlTok)
+    result = true # can progress
+
+#[ ========================================== ]
+ | nlTokBuilder Char Stream Reading Interface ]
+ ]#
+      
+# Read the next char in the stream without
+# checking whether it is safe to do so
+proc forceReadChar(builder: var nlTokBuilder) {.inline.} = 
+  echo "read"
+  inc builder.pos
+  builder.char = builder.stream.readChar()
+  builder.cTKind = getTokKind(builder.char)
+  builder.line.add(builder.char)
+
+# Read the next char in the stream
+# NOTE: readChar raises IOError on error, returns \0 on EOF
+proc readChar(builder: var nlTokBuilder): bool =
+  if builder.atEOL():
+    echo "EOL DETECT 2"
+    inc builder.lineNum
+  # sets builder.char to '\0' if EOF
+  builder.forceReadChar()
+  result = builder.atEOF()
+
+# Read until EOL and return the current line
+# NOTE: Does NOT update the builder's state (unsafe)
+# NOTE: ONLY call if a lex/parse error needs displaying
+proc unsafeGetLine(builder: var nlTokBuilder): string =
+  while not builder.atEOL() and builder.readChar():
+    discard
+  result = builder.line

src/noether/lexer/tokbuilding.nim

@@ -1,86 +0,0 @@
-include lstream
-
-type
-  # Provides a stream-like interface for lexing nlToks
-  # Internally reliant on the functionality of nlLStream
-  nlTokStream* = object
-    lstream: nlLStream
-    build: nlTok   # the build token
-    currTok*: nlTok # the current token
-    closed: bool # EOF + all tokens built
-
-# Generates an EOL token for the nlTokStream's state
-proc EOLTok(tokStream: nlTokStream): nlTok = 
-  result = nlTok(
-    tKind: tkEOL,
-    lit: "\0",
-    lineNum: Natural tokStream.lstream.lineNum,
-    startPos: Natural tokStream.lstream.pos,
-    endPos: Natural tokStream.lstream.pos,
-  )
-
-# Resets the build token to an "empty" nlTok
-proc resetBuild(tokStream: var nlTokStream) =
-  tokStream.build = emptyTok(tokStream.lstream.pos)
-
-# Completes a token generated by emptyTok()
-# based on the nlTokStream's nlLStream's
-# current line and character positions
-proc finishBuild(ts: var nlTokStream) =
-  ts.build.lineNum = Natural ts.lstream.lineNum
-  ts.build.endPos = Natural ts.lstream.pos
-  ts.build.lit = ts.lstream.line[ts.build.startPos ..< ts.build.endPos]
-
-# Returns the nlTokStream's build token and
-# empties the build token's contents.
-proc flushBuild(tokStream: var nlTokStream): nlTok = 
-  finishBuild(tokStream)
-  result = tokStream.build
-  resetBuild(tokStream)
-
-# Returns whether the build token has a set type yet.
-# This indicates that the build token should inherit
-# the nlTokKind of the nlLStream's next character.
-proc isUntypedBuild(tokStream: nlTokStream): bool =
-  result = tokStream.build.tKind.isUntyped()
-
-# Check whether an nlTokKind is "compatible" with the build token. 
-# NOTE: flushBuild() should be called when an incompatible token is discovered.
-proc isCompatibleBuild(tokStream: nlTokStream, tKind: nlTokKind): bool =
-  result = (tKind == tokStream.build.tKind)
-
-# Add a character to the nlTokStream's build token.
-# Flushes and returns the build token if "fully built",
-# and a boolean indicating whether the nlTokStream can progress.
-proc progressBuild(tokStream: var nlTokStream, buildTok: var Option[nlTok]): bool =
-  # the "pos > EOL" invalid state is used intentionally
-  # to indicate all tokens have been built, and return EOL Token
-  if tokStream.lstream.outOfBounds():
-    buildTok = some(EOLTok(tokStream))
-    return true # can progress once more
-    
-  let tKind = getTokType(tokStream.lstream.currChar())
-  # untyped build tokens must inherited immediately
-  if isUntypedBuild(tokStream):
-    tokStream.build.tKind = tKind
-  
-  # check if EOL reached
-  if tokStream.lstream.atEOL():
-      # flush old build token, the new one can be left untyped
-      let compatible = isCompatibleBuild(tokStream, tKind)
-      result = false # DO NOT PROGRESS
-      if compatible:
-        # force the lstream into an invalid state by progressing beyond EOL
-        # we can then detect this state on the next progressBuild and return
-        # an EOL character (very unsafe implementation but it works well)
-        tokStream.lstream.forceProgressChar()
-      buildTok = some(flushBuild(tokStream))
-  # check character and build token compatability
-  elif not isCompatibleBuild(tokStream, tKind):
-      # flush old build token, the new one inherits type
-      buildTok = some(flushBuild(tokStream))
-      tokStream.build.tKind = tKind
-      result = true # can progress
-  else:
-    buildTok = none(nlTok)
-    result = true # can progress

src/noether/lexer/tokkind.nim

@@ -29,9 +29,11 @@ type
     tkHASH, # # Number Sign (Hashtag)
         
 # Classifies a character to its nlTokKind
-proc getTokType*(c: char): nlTokKind =
+proc getTokKind*(c: char): nlTokKind =
   case c:
-  of '\0', '\r', '\n':
+  of '\0':
+    result = tkEOF
+  of '\r', '\n':
     result = tkEOL
   of ' ', '\t':
     result = tkWTSP

src/noether/lexer/tokstream.nim

@@ -1,52 +1,53 @@
-include tokbuilding
+include tokbuilder
+
+type
+  # Provides a stream-like interface for lexing.
+  # Implemented as a wrapper for nlTokBuilder.
+  nlTokStream* = object
+    builder: nlTokBuilder
+    tok*: nlTok # the current token
+    isClosed: bool # EOF + all tokens built
 
 # Initialises a new nlTokStream on a string or file
-proc newTokStream*(content: string, isFile: bool = false): nlTokStream =
+proc newTokStream*(stream: var Stream): nlTokStream =
   result = nlTokStream(
-    lstream: newLStream(content, isFile=isFile),
-    closed: false,
+    builder: newBuilder(stream),
+    tok: emptyTok(0),
+    isClosed: false,
   )
-  # 1. initialise an empty build token 
-  # 2. progress to the first line
-  result.resetBuild()
-  discard result.lstream.progressLine()
   
-# Defines a short-hand notation for getting the current line
-proc line*(tokStream: nlTokStream): string =
-  result = tokStream.lstream.line
-  
-# Reimplements nlLStream.progressChar for nlTokStream
-# to account for additional structure (ie the build token)
-# NOTE: progressChar progresses to lstream's next char
-proc progressChar(tokStream: var nlTokStream): bool =
-  if not tokStream.lstream.atEOL():
-    tokStream.lstream.forceProgressChar()
-    result = true
-  else:
-    # attempt to progress to next line past EOL
-    result = tokStream.lstream.progressLine()
-    tokStream.resetBuild()  
+# Expose a subset of the nlTokBuilder interface
+proc line*(stream: nlTokStream): string =
+  result = stream.builder.line
+proc atEOL*(stream: nlTokStream): bool = 
+  result = stream.builder.atEOL()
     
 # Generates and progress the next token in the nlTokStream.
 # via repeatedly calling progressBuild() and progressChar().
 # Returns a boolean indicating whether EOF has been reached.
-# NOTE: access the new token via `tokStream.tok`
-proc progress*(tokStream: var nlTokStream): bool =
+# NOTE: access the new token via `stream.tok`
+proc progress*(stream: var nlTokStream): bool =
   # Return prematurely if already closed
-  if tokStream.closed:
+  if stream.isClosed:
     return false
   while true:
+    # echo "\nProgressing..."
     var flushedTok: Option[nlTok]
     let 
-      canProgress = tokStream.progressBuild(flushedTok)
-      buildComplete = flushedTok.isSome
+      atEOF = stream.builder.readChar()
+      newTokBuilt = flushedTok.isSome
+    discard stream.builder.appendBuild(flushedTok)
+    echo flushedTok
+    echo "atEOF: ", atEOF, "\nnewTokBuilt: ", newTokBuilt
     # canProgress & EOF reached => no more tokens to build :)
     # NOTE: reachedEOF and not canProgress => more tokens unwrapping
-    if buildComplete:
+    if newTokBuilt:
       # return the finished build token, and save it as the current token
-      tokStream.currTok = flushedTok.get()
-    if canProgress and not tokStream.progressChar():
-      tokStream.closed = true
-      return buildComplete
-    elif buildComplete:
+      stream.tok = flushedTok.get()
+    # if canProgress and atEOF:
+    if atEOF:
+      if newTokBuilt:
+        stream.isClosed = true
+      return newTokBuilt
+    elif newTokBuilt:
       return true

src/noether/lib/io.nim

@@ -0,0 +1,7 @@
+import std/streams
+
+proc streamFile*(filename: string): Stream {.inline.} =
+  result = newFileStream(filename, fmRead)
+  
+proc streamString*(str: string): Stream {.inline.} =
+  result = newStringStream(str)