Let: Let works now, somehow. I fixed a bunch of things but this cart is still fundimentaly broken

src/fsh.nim

@@ -10,7 +10,8 @@ import os
 import strutils
 
 # globals
-var shellVariables = newStringTable(modeCaseSensitive)
+# shellVariables are an array of vars
+var shellVariables = @[newStringTable(modeCaseSensitive)]
 # Environment variables get defined in a separate var
 var envVariables = newStringTable(modeCaseSensitive)
 # populate the table
@@ -18,15 +19,19 @@ for k, v in envPairs():
   envVariables[k]=v
 
 # list of builtin commands
-let builtins: array[6, string] = [
+let builtins: array[7, string] = [
 "set",
 "setenv",
 "echo",
 "exit",
 "if",
 "cd",
+"let",
 ]
 
+# number of frames to be used for builtins like set
+var numframes: int=1
+
 # Exception types
 type
   ShellError= object of CatchableError
@@ -88,8 +93,10 @@ proc readLiteral(strm: Stream): string =
     case c:
       of '{':
         numbraces.inc
+        result.add('{')
       of '}':
         numbraces = numbraces - 1
+        if numbraces != 0: result.add('}')
       of '\\':
         if strm.peekChar notin {'{', '}'}: result.add(strm.readChar)
         result.add(strm.readChar)
@@ -191,9 +198,10 @@ proc readVariable(strm: Stream): string =
 # evalVariable finds a value of a variable
 proc evalVariable(vari: string): string =
   if vari == "$": return "$"
-  if shellVariables.hasKey(vari):
-    result=shellVariables[vari]
-  elif envVariables.hasKey(vari):
+  for i in countdown((numframes-1), 0):
+    let frame = shellVariables[i]
+    if frame.hasKey(vari): return frame[vari]
+  if envVariables.hasKey(vari):
     result = envVariables[vari]
   else:
     raise newShellVariableException("No such variable", vari)
@@ -252,7 +260,7 @@ proc runBuiltin(builtin: string, args: openArray[string]): (string, int) =
     of "set":
       if args.len < 2:
         raise newShellCommandException("Not enough arguments provided", "set")
-      shellVariables[args[0]] = args[1..^1].join(" ")
+      shellVariables[numframes-1][args[0]] = args[1..^1].join(" ")
       return ("", 0)
     of "setenv":
       if args.len < 2:
@@ -310,20 +318,37 @@ proc runBuiltin(builtin: string, args: openArray[string]): (string, int) =
     of "cd":
       try:
         if args.len == 0:
-          shellVariables["LASTPWD"] = getCurrentDir()
+          shellVariables[0]["LASTPWD"] = getCurrentDir()
           setCurrentDir(getHomeDir())
           return ("", 0)
         else:
           if args[0] == "-":
             let LASTPWD = getCurrentDir()
-            setCurrentDir(shellVariables["LASTPWD"])
-            shellVariables["LASTPWD"] = LASTPWD
+            setCurrentDir(shellVariables[0]["LASTPWD"])
+            shellVariables[0]["LASTPWD"] = LASTPWD
             return ("", 0)
-          shellVariables["LASTPWD"] = getCurrentDir()
+          shellVariables[0]["LASTPWD"] = getCurrentDir()
           setCurrentDir(args[0])
           return ("", 0)
       except OsError as e:
         raise newShellCommandException("No such directory", "cd")
+    of "let":
+      if args.len < 2:
+        raise newShellCommandException("Not enough arguments provided", "let")
+      shellVariables.add(newStringTable(modeCaseSensitive))
+      numframes.inc
+      let varvals = args[0].parseCommand
+      for varval in varvals:
+        let varval_parsed = varval.parseCommand
+        if varval_parsed.len < 2:
+          raise newShellCommandException("Missingvalue to go with key", "let")
+        let vari = varval_parsed[0]
+        let val = varval_parsed[1]
+        shellVariables[numframes-1][vari]=val
+      result[0] = args[1].eval
+      discard shellVariables.pop
+      numframes.dec
+      result[1] = 0
     else:
       raise newShellCommandException("No such builtin implemented", builtin)
 
@@ -374,12 +399,12 @@ when isMainModule:
   setControlCHook(ctrlc)
   let stdinstrm = stdin.newFileStream
   # Set the default prompt
-  shellVariables["PROMPT"] = "$PWD \\$"
-  stdout.write(shellVariables["PROMPT"].newStringStream.substitute)
+  shellVariables[0]["PROMPT"] = "$PWD \\$"
+  stdout.write(shellVariables[0]["PROMPT"].newStringStream.substitute)
   while not stdinstrm.atEnd():
     try:
       discard stdinstrm.readCommand.execute
-      stdout.write(shellVariables["PROMPT"].newStringStream.substitute)
+      stdout.write(shellVariables[0]["PROMPT"].newStringStream.substitute)
     except ShellError, ShellCommandError, ShellVariableError:
       let e = getCurrentException()
       stderr.write(e.msg, "\n")