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#
#
# The Nim Compiler
# (c) Copyright 2018 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## Layouter for nimpretty. Still primitive but useful.
## TODO
## - Fix 'echo ()' vs 'echo()' difference!
## - Make indentations consistent.
## - Align 'if' and 'case' expressions properly.
import idents, lexer, lineinfos, llstream, options, msgs, strutils
from os import changeFileExt
const
MaxLineLen = 80
LineCommentColumn = 30
type
SplitKind = enum
splitComma, splitParLe, splitAnd, splitOr, splitIn, splitBinary
Emitter* = object
f: PLLStream
config: ConfigRef
fid: FileIndex
lastTok: TTokType
inquote: bool
col, lastLineNumber, lineSpan, indentLevel: int
content: string
fixedUntil: int # marks where we must not go in the content
altSplitPos: array[SplitKind, int] # alternative split positions
proc openEmitter*(em: var Emitter, config: ConfigRef, fileIdx: FileIndex) =
let outfile = changeFileExt(config.toFullPath(fileIdx), ".pretty.nim")
em.f = llStreamOpen(outfile, fmWrite)
em.config = config
em.fid = fileIdx
em.lastTok = tkInvalid
em.inquote = false
em.col = 0
em.content = newStringOfCap(16_000)
if em.f == nil:
rawMessage(config, errGenerated, "cannot open file: " & outfile)
proc closeEmitter*(em: var Emitter) =
em.f.llStreamWrite em.content
llStreamClose(em.f)
proc countNewlines(s: string): int =
result = 0
for i in 0..<s.len:
if s[i] == '\L': inc result
proc calcCol(em: var Emitter; s: string) =
var i = s.len-1
em.col = 0
while i >= 0 and s[i] != '\L':
dec i
inc em.col
template wr(x) =
em.content.add x
inc em.col, x.len
template goodCol(col): bool = col in 40..MaxLineLen
const splitters = {tkComma, tkSemicolon, tkParLe, tkParDotLe,
tkBracketLe, tkBracketLeColon, tkCurlyDotLe,
tkCurlyLe}
template rememberSplit(kind) =
if goodCol(em.col):
em.altSplitPos[kind] = em.content.len
proc softLinebreak(em: var Emitter, lit: string) =
# XXX Use an algorithm that is outlined here:
# https://llvm.org/devmtg/2013-04/jasper-slides.pdf
# +2 because we blindly assume a comma or ' &' might follow
if not em.inquote and em.col+lit.len+2 >= MaxLineLen:
if em.lastTok in splitters:
wr("\L")
em.col = 0
for i in 1..em.indentLevel+2: wr(" ")
else:
# search backwards for a good split position:
for a in em.altSplitPos:
if a > em.fixedUntil:
let ws = "\L" & repeat(' ',em.indentLevel+2)
em.col = em.content.len - a
em.content.insert(ws, a)
break
proc emitTok*(em: var Emitter; L: TLexer; tok: TToken) =
template endsInWhite(em): bool =
em.content.len > 0 and em.content[em.content.high] in {' ', '\L'}
template endsInAlpha(em): bool =
em.content.len > 0 and em.content[em.content.high] in SymChars+{'_'}
proc emitComment(em: var Emitter; tok: TToken) =
let lit = strip fileSection(em.config, em.fid, tok.commentOffsetA, tok.commentOffsetB)
em.lineSpan = countNewlines(lit)
if em.lineSpan > 0: calcCol(em, lit)
if not endsInWhite(em):
wr(" ")
if em.lineSpan == 0 and max(em.col, LineCommentColumn) + lit.len <= MaxLineLen:
for i in 1 .. LineCommentColumn - em.col: wr(" ")
wr lit
var preventComment = false
if tok.tokType == tkComment and tok.line == em.lastLineNumber and tok.indent >= 0:
# we have an inline comment so handle it before the indentation token:
emitComment(em, tok)
preventComment = true
em.fixedUntil = em.content.high
elif tok.indent >= 0:
em.indentLevel = tok.indent
# remove trailing whitespace:
while em.content.len > 0 and em.content[em.content.high] == ' ':
setLen(em.content, em.content.len-1)
wr("\L")
for i in 2..tok.line - em.lastLineNumber: wr("\L")
em.col = 0
for i in 1..tok.indent:
wr(" ")
em.fixedUntil = em.content.high
case tok.tokType
of tokKeywordLow..tokKeywordHigh:
if endsInAlpha(em):
wr(" ")
elif not em.inquote and not endsInWhite(em):
wr(" ")
wr(TokTypeToStr[tok.tokType])
case tok.tokType
of tkAnd: rememberSplit(splitAnd)
of tkOr: rememberSplit(splitOr)
of tkIn, tkNotin:
rememberSplit(splitIn)
wr(" ")
else: discard
of tkColon:
wr(TokTypeToStr[tok.tokType])
wr(" ")
of tkSemicolon, tkComma:
wr(TokTypeToStr[tok.tokType])
wr(" ")
rememberSplit(splitComma)
of tkParLe, tkParRi, tkBracketLe,
tkBracketRi, tkCurlyLe, tkCurlyRi,
tkBracketDotLe, tkBracketDotRi,
tkCurlyDotLe, tkCurlyDotRi,
tkParDotLe, tkParDotRi,
tkColonColon, tkDot, tkBracketLeColon:
wr(TokTypeToStr[tok.tokType])
if tok.tokType in splitters:
rememberSplit(splitParLe)
of tkEquals:
if not em.endsInWhite: wr(" ")
wr(TokTypeToStr[tok.tokType])
wr(" ")
of tkOpr, tkDotDot:
if not em.endsInWhite: wr(" ")
wr(tok.ident.s)
template isUnary(tok): bool =
tok.strongSpaceB == 0 and tok.strongSpaceA > 0
if not isUnary(tok) or em.lastTok in {tkOpr, tkDotDot}:
wr(" ")
rememberSplit(splitBinary)
of tkAccent:
wr(TokTypeToStr[tok.tokType])
em.inquote = not em.inquote
of tkComment:
if not preventComment:
emitComment(em, tok)
of tkIntLit..tkStrLit, tkRStrLit, tkTripleStrLit, tkGStrLit, tkGTripleStrLit, tkCharLit:
let lit = fileSection(em.config, em.fid, tok.offsetA, tok.offsetB)
softLinebreak(em, lit)
if endsInAlpha(em) and tok.tokType notin {tkGStrLit, tkGTripleStrLit}: wr(" ")
em.lineSpan = countNewlines(lit)
if em.lineSpan > 0: calcCol(em, lit)
wr lit
of tkEof: discard
else:
let lit = if tok.ident != nil: tok.ident.s else: tok.literal
softLinebreak(em, lit)
if endsInAlpha(em): wr(" ")
wr lit
em.lastTok = tok.tokType
em.lastLineNumber = tok.line + em.lineSpan
em.lineSpan = 0
proc starWasExportMarker*(em: var Emitter) =
if em.content.endsWith(" * "):
setLen(em.content, em.content.len-3)
em.content.add("*")
dec em.col, 2
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