Don't allow begin_src header args :tangle val to be inherited

Author: kaushalmodi

src/ntangle.nim

@@ -1,7 +1,7 @@
 # NTangle - Basic tangling of Org documents
 # https://github.com/OrgTangle/ntangle
 
-import os, strformat, strutils, tables, terminal, sequtils
+import os, strformat, strutils, tables, terminal, sequtils, options
 
 type
   DebugVerbosity = enum dvNone, dvLow, dvHigh
@@ -43,7 +43,7 @@ type
   UserError = object of Exception
   OrgError = object of Exception
   HeaderArgs = object
-    tangle: string
+    tangle: Option[string]
     padline: bool
     shebang: string
     mkdirp: bool
@@ -85,7 +85,7 @@ proc resetStateVars() =
   fileHeaderArgs.clear()
   headerArgsDefaults.clear()
   # Default tangle header args for all Org levels and languages.
-  headerArgsDefaults[(0.Natural, "")] = HeaderArgs(tangle : "no",
+  headerArgsDefaults[(0.Natural, "")] = HeaderArgs(tangle : some("no"),
                                                    padline : true,
                                                    shebang : "",
                                                    mkdirp : false,
@@ -113,7 +113,8 @@ proc parseFilePermissions(octals: string): set[FilePermission] =
 proc parseTangleHeaderProperties(hdrArgs: seq[string], lnum: int, lang: string, onBeginSrc: bool) =
   ## Org header arguments related to tangling. See (org) Extracting Source Code.
   ## ``hdrArgs`` is a sequence like @["KEY1 VAL1", "KEY2 VAL2", ..].
-  let (dir, basename, _) = splitFile(orgFile)
+  let
+    (dir, basename, _) = splitFile(orgFile)
   dbg "Org file = {orgFile}, dir={dir}, base name={basename}", dvHigh
   dbg("", prefix=" ")           # blank line
   dbg "Line {lnum}, Lang {lang} - hdrArgs: {hdrArgs}"
@@ -140,12 +141,16 @@ proc parseTangleHeaderProperties(hdrArgs: seq[string], lnum: int, lang: string,
     dbg "Line {lnum} - Using only Org level {orgLevel} scope, now hArgs = {hArgs}"
 
   # If hArgs already specifies the tangled file path, use that!
-  if (hArgs.tangle != "yes") and (hArgs.tangle != "no"):
-    dbg "** Line {lnum} - Old outfile={outfile}, overriding it to {hArgs.tangle}"
-    if (not hArgs.tangle.startsWith "/"): # if relative path
-      outfile = dir / hArgs.tangle
+  if hArgs.tangle.isSome() and
+     (hArgs.tangle.get() != "yes") and
+     (hArgs.tangle.get() != "no"):
+    let
+      tangledPath = hArgs.tangle.get()
+    dbg "** Line {lnum} - Old outfile={outfile}, overriding it to {tangledPath}"
+    if (not tangledPath.startsWith "/"): # if relative path
+      outfile = dir / tangledPath
     else:
-      outfile = hArgs.tangle
+      outfile = tangledPath
 
   for hdrArg in hdrArgs:
     let
@@ -155,7 +160,7 @@ proc parseTangleHeaderProperties(hdrArgs: seq[string], lnum: int, lang: string,
     dbg "arg={arg}, argval={argval}, onBeginSrc={onBeginSrc}, outfile={outfile}"
     case arg
     of "tangle":
-      hArgs.tangle = argval
+      hArgs.tangle = some(argval)
       case argval
       of "yes":
         discard
@@ -235,24 +240,35 @@ proc parseTangleHeaderProperties(hdrArgs: seq[string], lnum: int, lang: string,
       discard
 
     # Update the default HeaderArgs for the current orgLevel+lang
-    # scope.
-    if (not onBeginSrc):      # global or subtree property
+    # scope, but only using the header args set using property keyword
+    # or the drawer property.
+    if (not onBeginSrc):
+      dbg "** Line {lnum}: Updating headerArgsDefaults[({orgLevel}, {lang})] to {hArgs}"
       headerArgsDefaults[(orgLevel, lang)] = hArgs
 
   dbg "[after] Line {lnum} - hArgs = {hArgs}"
-  # Save the updated hArgs to the file-specific HeaderArgs global
-  # value.
   if outfile != "":
+    # Save the updated hArgs to the file-specific HeaderArgs global
+    # value.
     outFileName = outfile
-    dbg "** outFileName now set to {outFileName}"
+    dbg "** Line {lnum}: Updating fileHeaderArgs[{outFileName}] to {hArgs}"
     fileHeaderArgs[outFileName] = hArgs
 
-  dbg "line={lnum}, onBeginSrc={onBeginSrc}, hArgs.tangle={hArgs.tangle} outfile={outfile} | outFileName={outFileName}"
-  if onBeginSrc and (hArgs.tangle != "no"):
-    doAssert outFileName != ""
-    dbg "line {lnum}: buffering enabled for `{outFileName}'"
-    bufEnabled = true
-    firstLineSrcBlock = true
+    dbg "line={lnum}, onBeginSrc={onBeginSrc}, hArgs.tangle={hArgs.tangle} outfile={outfile} | outFileName={outFileName}"
+    if onBeginSrc:
+      if hArgs.tangle.isSome() and
+         hArgs.tangle.get() != "no":
+        doAssert outFileName != ""
+        dbg "line {lnum}: buffering enabled for `{outFileName}'"
+        bufEnabled = true
+        firstLineSrcBlock = true
+
+      # Don't allow further source blocks to inherit the hArgs.tangle
+      # value set in begin_src header args.
+      hArgs.tangle = none(string)
+
+    dbg "** Line {lnum}: Updating fileHeaderArgs[{outFileName}] to {hArgs}"
+    fileHeaderArgs[outFileName] = hArgs
 
 proc orgRemoveEscapeCommas(line: string): string =
   ## Remove only single leading comma if it's followed by "#+" or "*".