-- Copyright (C) 2012, Gabriel Dos Reis.
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are
-- met:
--
--     - Redistributions of source code must retain the above copyright
--       notice, this list of conditions and the following disclaimer.
--
--     - Redistributions in binary form must reproduce the above copyright
--       notice, this list of conditions and the following disclaimer in
--       the documentation and/or other materials provided with the
--       distribution.
--
--     - Neither the name of OpenAxiom. nor the names of its contributors
--       may be used to endorse or promote products derived from this
--       software without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
-- IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
-- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
-- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
-- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
-- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
-- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
-- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import sys_-constants

namespace BOOT

module io where
  blankChar? : %Char -> %Boolean
  firstNonblankCharPosition: %String -> %Maybe %Short
  trimTrailingBlank: %String -> %String

--%
--%  Individual character routines
--%

++ Return true if character `c' is a space character.
macro spaceChar? c ==
  c = char " "

++ Return true if character `c' is a horizontal tab character
macro tabChar? c ==
  c = abstractChar 9
  

++ Return true if character `c' is either a space or a horitonal tab.
blankChar? c ==
  spaceChar? c or tabChar? c

carriageRetChar? c ==
  c = abstractChar 13


--%
--% String manipulation routines.
--%

++ Replace all characters in `s' with space characters.
storeBlank!(s,n) ==
  for i in 0..maxIndex s repeat
    s.i := char " "
  s

++ Return the position of the first nonblank character in line, if any.
firstNonblankCharPosition line ==
  or/[i for i in 0..maxIndex line | not blankChar? line.i]

trimTrailingBlank line ==
  n := sz := #line
  for i in (sz-1)..0 by -1 while blankChar? line.i repeat
    n := n - 1
  n = sz => line
  subString(line,0,n)

trimCarriageReturn line ==
  carriageRetChar? line.maxIndex(line) =>
    subString(line,0,maxIndex line)
  line

expandLeadingTabs line ==
  not string? line or #line = 0 => line
  line := trimCarriageReturn line
  nbLoc := firstNonblankCharPosition line
  indLoc := indentationLocation line
  nbLoc = indLoc => line
  strconc(makeString(indLoc,char " "), subString(line,nbLoc))

++ Find the position at which `s1' matches a substring of `s2',
++ starting from `k'.  Return nil on failure.
findString(s1,s2,k == 0) ==
  n1 := #s1
  or/[i for i in k..(#s2 - n1) |
        and/[stringChar(s1,j) = stringChar(s2,i+j) for j in 0..(n1-1)]]

--%
--% Source line
--%   string and line number
--%
structure %SourceLine ==
  Record(str: %String,no: %Short) with
    sourceLineString == (.str)
    sourceLineNumber == (.no)

makeSourceLine(s,n) ==
  mk%SourceLine(s,n)

--%
--% Load Unit
--%
structure %LoadUnit ==
  Record(path: %Path,lines: %List %SourceLine) with
    loadUnitPath == (.path)
    loadUnitLines == (.lines)

readLoadUnitSource path ==
  lines := 
    istream := inputTextFile path
      or systemError ['"could not open file: ",:bright path]
    try
      [makeSourceLine(s,n) for n in 1.. while not eof? istream
         | (s := readLine istream) and s ~= %nothing]
    finally
      closeStream istream
  mk%LoadUnit(path,lines)

--%
--% Line abstract datatype
--%
structure %Line ==
   Record(buf: %String, cchar: %Char, cidx: %Short,
     lidx: %Short, no: %Short) with
       lineBuffer == (.buf)           -- input string buffer
       lineCurrentChar == (.cchar)    -- current character
       lineCurrentIndex == (.cidx)    -- current index
       lineLastIndex == (.lidx)       -- last valid index
       lineNumber == (.no)            -- line number

makeLine(buf == makeString 0, ch == charByName "Return",
          curIdx == 1, lstIdx == 0, no == 0) ==
  mk%Line(buf,ch,curIdx,lstIdx,no)

lineClear! l ==
  lineBuffer(l) := makeString 0
  lineCurrentChar(l) := charByName "Return"
  lineCurrentIndex(l) := 1
  lineLastIndex(l) := 0
  lineNumber(l) := 0

++ Sets string to be the next line stored in line
lineNewLine!(s,l,no == nil) ==
  sz := #s
  lineLastIndex(l) := sz - 1
  lineCurrentIndex(l) := 0
  lineCurrentChar(l) := sz > 0 and s.0 or charByName '"Return"
  lineBuffer(l) := s
  lineNumber(l) := no or (lineNumber l + 1)

++ Tests if line is empty or positioned past the last character
lineAtEnd? l ==
  lineCurrentIndex l >= lineLastIndex l

++ Tests if line is empty or positioned past the last character
linePastEnd? l ==
  lineCurrentIndex l > lineLastIndex l

++ Buffer from current index to last index
lineCurrentSegment l ==
  lineAtEnd? l => makeString 0
  subSequence(lineBuffer l,lineCurrentIndex l,lineLastIndex l)

lineNextChar l ==
  lineBuffer(l).(1 + lineCurrentIndex l)

lineAdvanceChar! l ==
  n := lineCurrentIndex l + 1
  lineCurrentIndex(l) := n
  lineCurrentChar(l) := lineBuffer(l).n

--%
--% Reader
--%
structure %Reader ==
  Record(lu: %LoadUnit,est: %OutputStream,
    lines: %List %String,sline: %Line,idx: %Short,nxt: %SourceLine) with
      readerUnitSource == (.lu)     -- current load unit source
      readerError == (.est)         -- error output stream
      readerPendingLines == (.lines)
      readerSourceLine == (.sline)  -- current input line
      readerLineNumber == (.idx)    -- current line number
      readerNextLines == (.nxt)     -- next source line to process

makeReader(path,est) ==
  lu := readLoadUnitSource path
  mk%Reader(lu,est,nil,makeLine(),0,loadUnitLines lu)

readerEoi? rd ==
  readerNextLines rd = nil

readerReadLine rd ==
  readerNextLines rd is [x,:xs] =>
    readerNextLines(rd) := xs
    sourceLineString x
  %nothing    

++ Add line `l' to the stack of pending lines.
readerDeferLine(rd,l) ==
  readerPendingLines(rd) := [l,:readerPendingLines rd]

++ Print current line into to the reader's error stream.
readerPrintCurrentLine rd ==
  l := readerSourceLine rd
  if linePastEnd? l then
    formatToStream(readerError rd,'"~&The current line is empty.~%")
  else
    formatToStream(readerError rd,'"~&The current line is:~%~%")
    formatToStream(readerError rd,'"~&~5D> ~A~%",lineNumber l,lineBuffer l)
    formatToStream(readerError rd,'"~v@T^~%",lineCurrentIndex l + 7)