mini GNUPlot DSL in NIM

gnuplot_dsl.nim

# Generate gnuplot string from NIM DSL with variable substitution
# Author: Ugo Varetto

import macros, sets, sequtils, strutils, strformat, sugar

proc genCommands(node: NimNode, 
                 stmts: var seq[seq[string]],
                 cur: var seq[string],
                 commands: HashSet[string],
                 subst: bool = false): bool =
  #last list not added
  var substitute = false
  var inbracket = 0
  var separator = ","
  if node.kind == nnkIdent:
    if len(cur) > 0 and cur[^1] == "save" and node.strVal == "set":
       cur.add node.strVal
    elif node.strVal in commands:
      if len(cur) > 0 :
        stmts.add(cur)
      cur = newSeq[string]()
      cur.add node.strVal
    else:
      if node.strVal == "!":
        return true
      else:
        if subst:
          cur.add "{" & node.strVal & "}"
        else:
          cur.add node.strVal
  elif node.kind == nnkStrLit:
      cur.add fmt"'{node.strVal}'"
  elif node.kind == nnkIntLit:
      cur.add $node.intVal
  elif node.kind == nnkFloatLit:
      cur.add $node.floatVal
  elif node.kind == nnkBracket:
      cur.add "["
      inbracket = len(node)
      separator = ","
  elif node.kind == nnkExprColonExpr:
      separator = ":"
      inbracket = len(node)
  else:
    echo $node.kind

  for n in node.children:
    if inbracket > 0 and cur[^1] != "[":
      cur.add separator
    substitute = genCommands(n, stmts, cur, commands, substitute)
    if inbracket == 1:
      cur.add "]"
    if inbracket > 0:
      inbracket -= 1
  substitute

const commands = toHashSet(["set", "plot", "splot", "load", "save", "bind", "unset", "fit", "array", "stats", "FILE"])

macro gnuplot*(varname: untyped, body: untyped)=
  #parse line by line to keep same format
  echo body.toStrLit.strVal.split("\n")
  let t = parseStmt(body.toStrLit.strVal.split("\n")[1])
  var stm: seq[seq[string]]
  var cur: seq[string]
  discard genCommands(body, stm, cur, commands)
  if len(cur) > 0:
    stm.add(cur)
  let cmds = stm.map((x: seq[string]) -> string => x.join(" ")).join("\n")
  result = newStmtList(
    newConstStmt(varname, newStrLitNode(cmds))
  ) 

let color = "#0060ad"
gnuplot gpcommands:
  set style line 1 linecolor rgb color! linetype 1 linewidth 2
  set style line 4 linecolor rgb "#0660ad" linetype 1 linewidth 5
  plot [0:0.5] sin(x) "file.dat"
  set x [1,[2,4],3]

echo fmt $gpcommands