hilight

--[[
syntax hilighting

syntax hilighting methods

default colorscheme is based on pastebin's, but
more will be implemented later
--]]

local keywords={
  ["and"]=true, ["break"]=true, ["do"]=true, ["else"]=true, ["elseif"]=true,
  ["end"]=true, ["false"]=true, ["for"]=true, ["function"]=true, ["if"]=true,
  ["in"]=true, ["local"]=true, ["nil"]=true, ["not"]=true, ["or"]=true,
  ["repeat"]=true, ["return"]=true, ["then"]=true, ["true"]=true, ["until"]=true,
  ["while"]=true,
}

local hilight={
  keyword=colors.yellow,
  identifier=colors.white,
  number=colors.magenta,
  string=colors.pink,
  comment=colors.gray,
  operator=colors.green,
  ["error"]=colors.red,
}

function writeHilight(line, state, target)
  --tokenize
  if not target.isColor() then
    target.setTextColor(colors.white)
    target.write(line)
    return
  end
  target=target or term
  while #line>0 do
    if state.inComment then
      --look for end of comment block
      local comment,blockEnd,space,rest = line:match("^(.-)("..state.blockEnd..")(%s*)(.*)$")
      target.setTextColor(hilight.comment)
      if comment then
        target.write(comment..blockEnd..space)
        state.inComment=false
        state.blockEnd=nil
        line=rest
      else
        target.write(line)
        break
      end
    elseif state.inString then
      local str,blockEnd,space,rest = line:match("^(.-)("..state.blockEnd..")(%s*)(.*)$")
      target.setTextColor(hilight.string)
      if str then
        target.write(str..blockEnd..space)
        state.inString=false
        state.blockEnd=nil
        line=rest
      else
        target.write(line)
        break
      end
    else

      local word,space,rest=line:match("^([%a_][%a%d_]*)(%s*)(.*)$")
      if word then
        line=rest
        if keywords[word] then
          target.setTextColor(hilight.keyword)
        else
          target.setTextColor(hilight.identifier)
        end
        target.write(word..space)
      else
        local comment,rest=line:match("^(%-%-)(.*)$")
        target.setTextColor(hilight.comment)
        if comment then
          local block,mid,rest2 = rest:match("^(%[(=*)%[)(.*)$")
          if block then
            --begins block comment!
            state.inComment=true
            state.blockEnd="%]"..mid.."%]"
            line=rest2
            target.write(comment..block)
          else
            target.write(comment..rest)
            break
          end
        else
          local strBlk,mid,rest=line:match("^(%[(=*)%[)(.*)$")
          if strBlk then
            state.inString=true
            state.blockEnd="%]"..mid.."%]"
            line=rest
            target.setTextColor(hilight.string)
            target.write(strBlk)
          else
            local op,space,rest=line:match("^([%+%-%(%)%[%]%{%}/%*=<>%^:#~,;])(%s*)(.-)$")
            if op then
              line=rest
              target.setTextColor(hilight.operator)
              target.write(op..space)
            else
              local hex,space,rest=line:match("^(0x[%da-fA-F]*)(%s*)(.-)")
              if hex then
                line=rest
                target.setTextColor(hilight.number)
                target.write(hex..space)
              else
                local number,space,rest=line:match("^([%d]*%.?[%d]+)(%s*)(.-)$")
                if number then
                  line=rest
                  target.setTextColor(hilight.number)
                  target.write(number..space)
                else
                  local op,space,rest=line:match("^([%.]+)(%s*)(.-)$")
                  if op then
                    line=rest
                    target.setTextColor(hilight.operator)
                    target.write(op..space)
                  else
                    local strTok, rest = line:match("^([\"'])(.-)$")
                    if strTok then
                      line=rest
                      --find end
                      local str=""
                      local unterminated
                      while true do
                        local temp
                        temp,_,rest=line:match("^([^"..strTok.."]*)("..strTok..")(.*)$")
                        if temp then
                          line=rest
                          str=str..temp
                          if temp:sub(#temp)~="\\" then
                            break
                          end
                          str=str..strTok
                        else
                          unterminated=true
                          str=str..line
                          break
                        end
                      end
                      if unterminated then
                        target.setTextColor(hilight.error)
                        target.write(strTok..str)
                        break
                      else
                        target.setTextColor(hilight.string)
                        target.write(strTok..str..strTok)
                      end
                    else
                      local space,rest=line:match("^(%s+)(.*)$")
                      if space then
                        line=rest
                        target.write(space)
                      else
                        if #line>0 then
                          target.setTextColor(hilight.error)
                          target.write(line)
                        end
                        break
                      end
                    end
                  end
                end
              end
            end
          end
        end
      end
    end
  end
  target.setTextColor(colors.white)
end

function copyState(state)
  local state2={}
  if state then
    for k,v in pairs(state) do
      state2[k]=v
    end
  end
  return state2
end

function hilightToSpans(text,prevState)
  local nextColor=colors.white
  local state=copyState(prevState)
  local spans={rawText=text, state=state}


  local target={
    setTextColor=function(c) nextColor=c end,
    write=function(...)
        if #spans>0 and spans[#spans].color==nextColor then
          spans[#spans].text=spans[#spans].text..table.concat({...})
        else
          spans[#spans+1]={
            text=table.concat({...}),
            color=nextColor
          }
        end
      end,
    isColor=function() return term.isColor() end
  }

  writeHilight(text,state,target)

  return spans
end

function compareStates(stateA,stateB)
  return stateA.inString==stateB.inString and stateA.inComment==stateB.inComment and stateA.blockEnd==stateB.blockEnd
end


function writeSpans(spans)
  for i=1,#spans do
    term.setTextColor(spans[i].color)
    term.write(spans[i].text)
  end
  term.setTextColor(colors.white)
end

function interactiveTest()
  local spans={state={}}
  while true do
    write("\n>")
    local input=read()

    if #input==0 then
      break
    end
    spans=hilightToSpans(input,spans.state)

    writeSpans(spans)
  end
end

if shell then
  interactiveText()
end