2 % (c) The University of Glasgow, 1992-2006
6 -- | This module contains types that relate to the positions of things
7 -- in source files, and allow tagging of those things with locations
12 -- ** Constructing SrcLoc
13 mkSrcLoc, mkGeneralSrcLoc,
15 noSrcLoc, -- "I'm sorry, I haven't a clue"
16 generatedSrcLoc, -- Code generated within the compiler
17 interactiveSrcLoc, -- Code from an interactive session
21 -- ** Unsafely deconstructing SrcLoc
22 -- These are dubious exports, because they crash on some inputs
23 srcLocFile, -- return the file name part
24 srcLocLine, -- return the line part
25 srcLocCol, -- return the column part
27 -- ** Misc. operations on SrcLoc
30 -- ** Predicates on SrcLoc
36 -- ** Constructing SrcSpan
37 mkGeneralSrcSpan, mkSrcSpan,
39 wiredInSrcSpan, -- Something wired into the compiler
43 -- ** Deconstructing SrcSpan
44 srcSpanStart, srcSpanEnd,
45 srcSpanFileName_maybe,
47 -- ** Unsafely deconstructing SrcSpan
48 -- These are dubious exports, because they crash on some inputs
50 srcSpanStartLine, srcSpanEndLine,
51 srcSpanStartCol, srcSpanEndCol,
53 -- ** Predicates on SrcSpan
54 isGoodSrcSpan, isOneLineSpan,
59 -- ** Constructing Located
63 -- ** Deconstructing Located
66 -- ** Combining and comparing Located values
67 eqLocated, cmpLocated, combineLocs, addCLoc,
68 leftmost_smallest, leftmost_largest, rightmost,
82 %************************************************************************
84 \subsection[SrcLoc-SrcLocations]{Source-location information}
86 %************************************************************************
88 We keep information about the {\em definition} point for each entity;
89 this is the obvious stuff:
91 -- | Represents a single point within a file
93 = SrcLoc FastString -- A precise location (file name)
94 {-# UNPACK #-} !Int -- line number, begins at 1
95 {-# UNPACK #-} !Int -- column number, begins at 1
96 | UnhelpfulLoc FastString -- Just a general indication
99 %************************************************************************
101 \subsection[SrcLoc-access-fns]{Access functions}
103 %************************************************************************
106 mkSrcLoc :: FastString -> Int -> Int -> SrcLoc
107 mkSrcLoc x line col = SrcLoc x line col
109 -- | Built-in "bad" 'SrcLoc' values for particular locations
110 noSrcLoc, generatedSrcLoc, interactiveSrcLoc :: SrcLoc
111 noSrcLoc = UnhelpfulLoc (fsLit "<no location info>")
112 generatedSrcLoc = UnhelpfulLoc (fsLit "<compiler-generated code>")
113 interactiveSrcLoc = UnhelpfulLoc (fsLit "<interactive session>")
115 -- | Creates a "bad" 'SrcLoc' that has no detailed information about its location
116 mkGeneralSrcLoc :: FastString -> SrcLoc
117 mkGeneralSrcLoc = UnhelpfulLoc
119 -- | "Good" 'SrcLoc's have precise information about their location
120 isGoodSrcLoc :: SrcLoc -> Bool
121 isGoodSrcLoc (SrcLoc _ _ _) = True
122 isGoodSrcLoc _other = False
124 -- | Gives the filename of the 'SrcLoc' if it is available, otherwise returns a dummy value
125 srcLocFile :: SrcLoc -> FastString
126 srcLocFile (SrcLoc fname _ _) = fname
127 srcLocFile _other = (fsLit "<unknown file")
129 -- | Raises an error when used on a "bad" 'SrcLoc'
130 srcLocLine :: SrcLoc -> Int
131 srcLocLine (SrcLoc _ l _) = l
132 srcLocLine (UnhelpfulLoc s) = pprPanic "srcLocLine" (ftext s)
134 -- | Raises an error when used on a "bad" 'SrcLoc'
135 srcLocCol :: SrcLoc -> Int
136 srcLocCol (SrcLoc _ _ c) = c
137 srcLocCol (UnhelpfulLoc s) = pprPanic "srcLocCol" (ftext s)
139 -- | Move the 'SrcLoc' down by one line if the character is a newline,
140 -- to the next 8-char tabstop if it is a tab, and across by one
141 -- character in any other case
142 advanceSrcLoc :: SrcLoc -> Char -> SrcLoc
143 advanceSrcLoc (SrcLoc f l _) '\n' = SrcLoc f (l + 1) 1
144 advanceSrcLoc (SrcLoc f l c) '\t' = SrcLoc f l (((((c - 1) `shiftR` 3) + 1)
146 advanceSrcLoc (SrcLoc f l c) _ = SrcLoc f l (c + 1)
147 advanceSrcLoc loc _ = loc -- Better than nothing
150 %************************************************************************
152 \subsection[SrcLoc-instances]{Instance declarations for various names}
154 %************************************************************************
157 -- SrcLoc is an instance of Ord so that we can sort error messages easily
158 instance Eq SrcLoc where
159 loc1 == loc2 = case loc1 `cmpSrcLoc` loc2 of
163 instance Ord SrcLoc where
166 cmpSrcLoc :: SrcLoc -> SrcLoc -> Ordering
167 cmpSrcLoc (UnhelpfulLoc s1) (UnhelpfulLoc s2) = s1 `compare` s2
168 cmpSrcLoc (UnhelpfulLoc _) (SrcLoc _ _ _) = GT
169 cmpSrcLoc (SrcLoc _ _ _) (UnhelpfulLoc _) = LT
171 cmpSrcLoc (SrcLoc s1 l1 c1) (SrcLoc s2 l2 c2)
172 = (s1 `compare` s2) `thenCmp` (l1 `compare` l2) `thenCmp` (c1 `compare` c2)
174 instance Outputable SrcLoc where
175 ppr (SrcLoc src_path src_line src_col)
176 = getPprStyle $ \ sty ->
177 if userStyle sty || debugStyle sty then
178 hcat [ pprFastFilePath src_path, char ':',
180 char ':', int src_col
183 hcat [text "{-# LINE ", int src_line, space,
184 char '\"', pprFastFilePath src_path, text " #-}"]
186 ppr (UnhelpfulLoc s) = ftext s
188 instance Data SrcSpan where
190 toConstr _ = abstractConstr "SrcSpan"
191 gunfold _ _ = error "gunfold"
192 dataTypeOf _ = mkNoRepType "SrcSpan"
195 %************************************************************************
197 \subsection[SrcSpan]{Source Spans}
199 %************************************************************************
203 A SrcSpan delimits a portion of a text file. It could be represented
204 by a pair of (line,column) coordinates, but in fact we optimise
205 slightly by using more compact representations for single-line and
206 zero-length spans, both of which are quite common.
208 The end position is defined to be the column /after/ the end of the
209 span. That is, a span of (1,1)-(1,2) is one character long, and a
210 span of (1,1)-(1,1) is zero characters long.
213 = SrcSpanOneLine -- a common case: a single line
214 { srcSpanFile :: !FastString,
215 srcSpanLine :: {-# UNPACK #-} !Int,
216 srcSpanSCol :: {-# UNPACK #-} !Int,
217 srcSpanECol :: {-# UNPACK #-} !Int
221 { srcSpanFile :: !FastString,
222 srcSpanSLine :: {-# UNPACK #-} !Int,
223 srcSpanSCol :: {-# UNPACK #-} !Int,
224 srcSpanELine :: {-# UNPACK #-} !Int,
225 srcSpanECol :: {-# UNPACK #-} !Int
229 { srcSpanFile :: !FastString,
230 srcSpanLine :: {-# UNPACK #-} !Int,
231 srcSpanCol :: {-# UNPACK #-} !Int
234 | UnhelpfulSpan !FastString -- Just a general indication
235 -- also used to indicate an empty span
238 deriving (Eq, Typeable, Show) -- Show is used by Lexer.x, becuase we
239 -- derive Show for Token
241 deriving (Eq, Typeable)
244 -- | Built-in "bad" 'SrcSpan's for common sources of location uncertainty
245 noSrcSpan, wiredInSrcSpan :: SrcSpan
246 noSrcSpan = UnhelpfulSpan (fsLit "<no location info>")
247 wiredInSrcSpan = UnhelpfulSpan (fsLit "<wired into compiler>")
249 -- | Create a "bad" 'SrcSpan' that has not location information
250 mkGeneralSrcSpan :: FastString -> SrcSpan
251 mkGeneralSrcSpan = UnhelpfulSpan
253 -- | Create a 'SrcSpan' corresponding to a single point
254 srcLocSpan :: SrcLoc -> SrcSpan
255 srcLocSpan (UnhelpfulLoc str) = UnhelpfulSpan str
256 srcLocSpan (SrcLoc file line col) = SrcSpanPoint file line col
258 -- | Create a 'SrcSpan' between two points in a file
259 mkSrcSpan :: SrcLoc -> SrcLoc -> SrcSpan
260 mkSrcSpan (UnhelpfulLoc str) _ = UnhelpfulSpan str
261 mkSrcSpan _ (UnhelpfulLoc str) = UnhelpfulSpan str
263 | line1 == line2 = if col1 == col2
264 then SrcSpanPoint file line1 col1
265 else SrcSpanOneLine file line1 col1 col2
266 | otherwise = SrcSpanMultiLine file line1 col1 line2 col2
268 line1 = srcLocLine loc1
269 line2 = srcLocLine loc2
270 col1 = srcLocCol loc1
271 col2 = srcLocCol loc2
272 file = srcLocFile loc1
274 -- | Combines two 'SrcSpan' into one that spans at least all the characters
275 -- within both spans. Assumes the "file" part is the same in both inputs
276 combineSrcSpans :: SrcSpan -> SrcSpan -> SrcSpan
277 combineSrcSpans (UnhelpfulSpan _) r = r -- this seems more useful
278 combineSrcSpans l (UnhelpfulSpan _) = l
279 combineSrcSpans span1 span2
280 = if line_start == line_end
281 then if col_start == col_end
282 then SrcSpanPoint file line_start col_start
283 else SrcSpanOneLine file line_start col_start col_end
284 else SrcSpanMultiLine file line_start col_start line_end col_end
286 (line_start, col_start) = min (srcSpanStartLine span1, srcSpanStartCol span1)
287 (srcSpanStartLine span2, srcSpanStartCol span2)
288 (line_end, col_end) = max (srcSpanEndLine span1, srcSpanEndCol span1)
289 (srcSpanEndLine span2, srcSpanEndCol span2)
290 file = srcSpanFile span1
293 %************************************************************************
295 \subsection[SrcSpan-predicates]{Predicates}
297 %************************************************************************
300 -- | Test if a 'SrcSpan' is "good", i.e. has precise location information
301 isGoodSrcSpan :: SrcSpan -> Bool
302 isGoodSrcSpan SrcSpanOneLine{} = True
303 isGoodSrcSpan SrcSpanMultiLine{} = True
304 isGoodSrcSpan SrcSpanPoint{} = True
305 isGoodSrcSpan _ = False
307 isOneLineSpan :: SrcSpan -> Bool
308 -- ^ True if the span is known to straddle only one line.
309 -- For "bad" 'SrcSpan', it returns False
311 | isGoodSrcSpan s = srcSpanStartLine s == srcSpanEndLine s
316 %************************************************************************
318 \subsection[SrcSpan-unsafe-access-fns]{Unsafe access functions}
320 %************************************************************************
324 -- | Raises an error when used on a "bad" 'SrcSpan'
325 srcSpanStartLine :: SrcSpan -> Int
326 -- | Raises an error when used on a "bad" 'SrcSpan'
327 srcSpanEndLine :: SrcSpan -> Int
328 -- | Raises an error when used on a "bad" 'SrcSpan'
329 srcSpanStartCol :: SrcSpan -> Int
330 -- | Raises an error when used on a "bad" 'SrcSpan'
331 srcSpanEndCol :: SrcSpan -> Int
333 srcSpanStartLine SrcSpanOneLine{ srcSpanLine=l } = l
334 srcSpanStartLine SrcSpanMultiLine{ srcSpanSLine=l } = l
335 srcSpanStartLine SrcSpanPoint{ srcSpanLine=l } = l
336 srcSpanStartLine _ = panic "SrcLoc.srcSpanStartLine"
338 srcSpanEndLine SrcSpanOneLine{ srcSpanLine=l } = l
339 srcSpanEndLine SrcSpanMultiLine{ srcSpanELine=l } = l
340 srcSpanEndLine SrcSpanPoint{ srcSpanLine=l } = l
341 srcSpanEndLine _ = panic "SrcLoc.srcSpanEndLine"
343 srcSpanStartCol SrcSpanOneLine{ srcSpanSCol=l } = l
344 srcSpanStartCol SrcSpanMultiLine{ srcSpanSCol=l } = l
345 srcSpanStartCol SrcSpanPoint{ srcSpanCol=l } = l
346 srcSpanStartCol _ = panic "SrcLoc.srcSpanStartCol"
348 srcSpanEndCol SrcSpanOneLine{ srcSpanECol=c } = c
349 srcSpanEndCol SrcSpanMultiLine{ srcSpanECol=c } = c
350 srcSpanEndCol SrcSpanPoint{ srcSpanCol=c } = c
351 srcSpanEndCol _ = panic "SrcLoc.srcSpanEndCol"
355 %************************************************************************
357 \subsection[SrcSpan-access-fns]{Access functions}
359 %************************************************************************
363 -- | Returns the location at the start of the 'SrcSpan' or a "bad" 'SrcSpan' if that is unavailable
364 srcSpanStart :: SrcSpan -> SrcLoc
365 -- | Returns the location at the end of the 'SrcSpan' or a "bad" 'SrcSpan' if that is unavailable
366 srcSpanEnd :: SrcSpan -> SrcLoc
368 srcSpanStart (UnhelpfulSpan str) = UnhelpfulLoc str
369 srcSpanStart s = mkSrcLoc (srcSpanFile s)
373 srcSpanEnd (UnhelpfulSpan str) = UnhelpfulLoc str
375 mkSrcLoc (srcSpanFile s)
379 -- | Obtains the filename for a 'SrcSpan' if it is "good"
380 srcSpanFileName_maybe :: SrcSpan -> Maybe FastString
381 srcSpanFileName_maybe (SrcSpanOneLine { srcSpanFile = nm }) = Just nm
382 srcSpanFileName_maybe (SrcSpanMultiLine { srcSpanFile = nm }) = Just nm
383 srcSpanFileName_maybe (SrcSpanPoint { srcSpanFile = nm}) = Just nm
384 srcSpanFileName_maybe _ = Nothing
388 %************************************************************************
390 \subsection[SrcSpan-instances]{Instances}
392 %************************************************************************
396 -- We want to order SrcSpans first by the start point, then by the end point.
397 instance Ord SrcSpan where
399 (srcSpanStart a `compare` srcSpanStart b) `thenCmp`
400 (srcSpanEnd a `compare` srcSpanEnd b)
403 instance Outputable SrcSpan where
405 = getPprStyle $ \ sty ->
406 if userStyle sty || debugStyle sty then
407 pprUserSpan True span
409 hcat [text "{-# LINE ", int (srcSpanStartLine span), space,
410 char '\"', pprFastFilePath $ srcSpanFile span, text " #-}"]
412 pprUserSpan :: Bool -> SrcSpan -> SDoc
413 pprUserSpan show_path (SrcSpanOneLine src_path line start_col end_col)
414 = hcat [ ppWhen show_path (pprFastFilePath src_path <> colon)
415 , int line, char ':', int start_col
416 , ppUnless (end_col - start_col <= 1)
417 (char '-' <> int (end_col-1))
418 -- For single-character or point spans, we just
419 -- output the starting column number
423 pprUserSpan show_path (SrcSpanMultiLine src_path sline scol eline ecol)
424 = hcat [ ppWhen show_path (pprFastFilePath src_path <> colon)
425 , parens (int sline <> char ',' <> int scol)
427 , parens (int eline <> char ',' <>
428 if ecol == 0 then int ecol else int (ecol-1))
431 pprUserSpan show_path (SrcSpanPoint src_path line col)
432 = hcat [ ppWhen show_path $ (pprFastFilePath src_path <> colon)
433 , int line, char ':', int col ]
435 pprUserSpan _ (UnhelpfulSpan s) = ftext s
437 pprDefnLoc :: SrcSpan -> SDoc
438 -- ^ Pretty prints information about the 'SrcSpan' in the style "defined at ..."
440 | isGoodSrcSpan loc = ptext (sLit "Defined at") <+> ppr loc
441 | otherwise = ppr loc
444 %************************************************************************
446 \subsection[Located]{Attaching SrcSpans to things}
448 %************************************************************************
451 -- | We attach SrcSpans to lots of things, so let's have a datatype for it.
452 data Located e = L SrcSpan e
453 deriving (Eq, Ord, Typeable, Data)
455 unLoc :: Located e -> e
458 getLoc :: Located e -> SrcSpan
461 noLoc :: e -> Located e
462 noLoc e = L noSrcSpan e
464 mkGeneralLocated :: String -> e -> Located e
465 mkGeneralLocated s e = L (mkGeneralSrcSpan (fsLit s)) e
467 combineLocs :: Located a -> Located b -> SrcSpan
468 combineLocs a b = combineSrcSpans (getLoc a) (getLoc b)
470 -- | Combine locations from two 'Located' things and add them to a third thing
471 addCLoc :: Located a -> Located b -> c -> Located c
472 addCLoc a b c = L (combineSrcSpans (getLoc a) (getLoc b)) c
474 -- not clear whether to add a general Eq instance, but this is useful sometimes:
476 -- | Tests whether the two located things are equal
477 eqLocated :: Eq a => Located a -> Located a -> Bool
478 eqLocated a b = unLoc a == unLoc b
480 -- not clear whether to add a general Ord instance, but this is useful sometimes:
482 -- | Tests the ordering of the two located things
483 cmpLocated :: Ord a => Located a -> Located a -> Ordering
484 cmpLocated a b = unLoc a `compare` unLoc b
486 instance Functor Located where
487 fmap f (L l e) = L l (f e)
489 instance Outputable e => Outputable (Located e) where
490 ppr (L l e) = ifPprDebug (braces (pprUserSpan False l)) $$ ppr e
491 -- Print spans without the file name etc
494 %************************************************************************
496 \subsection{Ordering SrcSpans for InteractiveUI}
498 %************************************************************************
501 -- | Alternative strategies for ordering 'SrcSpan's
502 leftmost_smallest, leftmost_largest, rightmost :: SrcSpan -> SrcSpan -> Ordering
503 rightmost = flip compare
504 leftmost_smallest = compare
505 leftmost_largest a b = (srcSpanStart a `compare` srcSpanStart b)
507 (srcSpanEnd b `compare` srcSpanEnd a)
510 -- | Determines whether a span encloses a given line and column index
511 spans :: SrcSpan -> (Int, Int) -> Bool
512 spans span (l,c) = srcSpanStart span <= loc && loc <= srcSpanEnd span
513 where loc = mkSrcLoc (srcSpanFile span) l c
515 -- | Determines whether a span is enclosed by another one
516 isSubspanOf :: SrcSpan -- ^ The span that may be enclosed by the other
517 -> SrcSpan -- ^ The span it may be enclosed by
519 isSubspanOf src parent
520 | srcSpanFileName_maybe parent /= srcSpanFileName_maybe src = False
521 | otherwise = srcSpanStart parent <= srcSpanStart src &&
522 srcSpanEnd parent >= srcSpanEnd src