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lexer, common: More descriptive error messages.

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The lexer now tracks the data that has been read since the start of the
current line. While this may have use in parsers, the immediate use is
by the common error reporting procedure.

The `common#error` procedure already reports the column and line number
where an error occurs. The `common#expect` function is broadly used by
parsers and generates the majority of parser errors. It now uses the
lexer's record of the current line to format its error message with a
direct pointer to the location of the unmet expectation.
This commit is contained in:
Jonathan Bernard 2023-05-02 22:11:00 -05:00
parent 71107dda1c
commit 8e25c3d100
2 changed files with 26 additions and 16 deletions
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28
src/vcard/private/common.nim
View File

@ -57,7 +57,7 @@ func serialize*(s: seq[VC_XParam]): string =
# ============================================================================= # =============================================================================
proc error*(p: VCardParser, msg: string) = proc error*(p: VCardParser, msg: string) =
raise newException(VCardParsingError, "$1($2, $3) Error: $4] " % raise newException(VCardParsingError, "$1($2, $3) Error: $4" %
[ p.filename, $p.lineNumber, $p.getColNumber(p.pos), msg ]) [ p.filename, $p.lineNumber, $p.getColNumber(p.pos), msg ])
proc isNext*[T](p: var T, expected: string, caseSensitive = false): bool = proc isNext*[T](p: var T, expected: string, caseSensitive = false): bool =
@ -79,21 +79,23 @@ proc isNext*[T](p: var T, expected: string, caseSensitive = false): bool =
p.returnToBookmark p.returnToBookmark
proc expect*[T](p: var T, expected: string, caseSensitive = false) = proc expect*[T](p: var T, expected: string, caseSensitive = false) =
p.setBookmark try:
p.setBookmark
if caseSensitive: if caseSensitive:
for ch in expected: for ch in expected:
if p.read != ch: if p.read != ch: raise newException(ValueError, "")
p.error("expected '$1' but found '$2'" % else:
[expected, p.readSinceBookmark]) for rune in expected.runes:
if p.readRune.toLower != rune.toLower:
raise newException(ValueError, "")
else: except ValueError:
for rune in expected.runes: p.error("expected '$1' but found '$2':\n\t$3\n\t$4" %
if p.readRune.toLower != rune.toLower: [expected, p.readSinceBookmark, p.lineVal,
p.error("expected '$1' but found '$2'" % " ".repeat(p.getColNumber(p.pos) - 1) & "^\n"])
[ expected, p.readSinceBookmark ])
p.unsetBookmark finally: p.unsetBookmark
proc readGroup*[T](p: var T): Option[string] = proc readGroup*[T](p: var T): Option[string] =
## All VCARD content items can be optionally prefixed with a group name. This ## All VCARD content items can be optionally prefixed with a group name. This

14
src/vcard/private/lexer.nim
View File

@ -11,6 +11,7 @@ type VCardLexer* = object of RootObj
bookmarkVal*: seq[string] # value read since the bookmark was set bookmarkVal*: seq[string] # value read since the bookmark was set
lineNumber*: int # how many newlines have we seen so far lineNumber*: int # how many newlines have we seen so far
lineStart: int # buffer index buffer for the start of the current line lineStart: int # buffer index buffer for the start of the current line
lineVal*: string # value read since the start of the current line
proc skipUtf8Bom(vcl: var VCardLexer) = proc skipUtf8Bom(vcl: var VCardLexer) =
if (vcl.buffer[0] == '\xEF') and (vcl.buffer[1] == '\xBB') and (vcl.buffer[2] == '\xBF'): if (vcl.buffer[0] == '\xEF') and (vcl.buffer[1] == '\xBB') and (vcl.buffer[2] == '\xBF'):
@ -137,16 +138,18 @@ proc read*(vcl: var VCardLexer, peek = false): char =
vcl.pos += 3 vcl.pos += 3
vcl.lineNumber += 1 vcl.lineNumber += 1
vcl.lineStart = vcl.pos vcl.lineStart = vcl.pos
vcl.lineVal = newStringOfCap(84)
if vcl.atEnd: vcl.fillBuffer() if vcl.atEnd: vcl.fillBuffer()
elif vcl.buffer[vcl.pos] == '\n': elif vcl.buffer[vcl.pos] == '\n':
vcl.lineNumber += 1 vcl.lineNumber += 1
vcl.lineStart = wrappedIdx(vcl.pos + 1) vcl.lineStart = wrappedIdx(vcl.pos + 1)
vcl.lineVal = newStringOfCap(84)
result = vcl.buffer[vcl.pos] result = vcl.buffer[vcl.pos]
if not peek: if not peek:
for idx in 0..<vcl.bookmarkVal.len: for idx in 0..<vcl.bookmarkVal.len: vcl.bookmarkVal[idx].add(result)
vcl.bookmarkVal[idx].add(result) vcl.lineVal.add(result)
vcl.pos = wrappedIdx(vcl.pos + 1) vcl.pos = wrappedIdx(vcl.pos + 1)
proc readLen*(vcl: var VCardLexer, bytesToRead: int, peek = false): string = proc readLen*(vcl: var VCardLexer, bytesToRead: int, peek = false): string =
@ -160,14 +163,19 @@ proc readRune*(vcl: var VCardLexer, peek = false): Rune =
vcl.pos += 3 vcl.pos += 3
vcl.lineNumber += 1 vcl.lineNumber += 1
vcl.lineStart = vcl.pos vcl.lineStart = vcl.pos
vcl.lineVal = newStringOfCap(84)
if vcl.atEnd: vcl.fillBuffer() if vcl.atEnd: vcl.fillBuffer()
elif vcl.buffer[vcl.pos] == '\n': elif vcl.buffer[vcl.pos] == '\n':
vcl.lineNumber += 1 vcl.lineNumber += 1
vcl.lineStart = wrappedIdx(vcl.pos + 1) vcl.lineStart = wrappedIdx(vcl.pos + 1)
vcl.lineVal = newStringOfCap(84)
result = vcl.buffer.runeAt(vcl.pos) result = vcl.buffer.runeAt(vcl.pos)
if not peek: vcl.pos += vcl.buffer.runeLenAt(vcl.pos) if not peek:
for idx in 0..<vcl.bookmarkVal.len: vcl.bookmarkVal[idx].add(result)
vcl.lineVal.add(result)
vcl.pos += vcl.buffer.runeLenAt(vcl.pos)
proc readRunesLen*(vcl: var VCardLexer, runesToRead: int, peek = false): string = proc readRunesLen*(vcl: var VCardLexer, runesToRead: int, peek = false): string =
result = newStringOfCap(runesToRead * 4) result = newStringOfCap(runesToRead * 4)