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413 lines
13 KiB
Nim
413 lines
13 KiB
Nim
#
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#
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# Nimrod's Runtime Library
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## This module contains helpers for parsing tokens, numbers, identifiers, etc.
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{.deadCodeElim: on.}
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{.push debugger:off .} # the user does not want to trace a part
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# of the standard library!
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include "system/inclrtl"
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const
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Whitespace = {' ', '\t', '\v', '\r', '\l', '\f'}
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IdentChars = {'a'..'z', 'A'..'Z', '0'..'9', '_'}
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IdentStartChars = {'a'..'z', 'A'..'Z', '_'}
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## copied from strutils
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proc toLower(c: char): char {.inline.} =
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result = if c in {'A'..'Z'}: chr(ord(c)-ord('A')+ord('a')) else: c
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proc parseHex*(s: string, number: var int, start = 0): int {.
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rtl, extern: "npuParseHex", noSideEffect.} =
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## Parses a hexadecimal number and stores its value in ``number``.
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##
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## Returns the number of the parsed characters or 0 in case of an error. This
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## proc is sensitive to the already existing value of ``number`` and will
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## likely not do what you want unless you make sure ``number`` is zero. You
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## can use this feature to *chain* calls, though the result int will quickly
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## overflow. Example:
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##
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## .. code-block:: nimrod
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## var value = 0
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## discard parseHex("0x38", value)
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## assert value == 56
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## discard parseHex("0x34", value)
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## assert value == 56 * 256 + 52
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## value = -1
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## discard parseHex("0x38", value)
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## assert value == -200
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##
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var i = start
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var foundDigit = false
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if s[i] == '0' and (s[i+1] == 'x' or s[i+1] == 'X'): inc(i, 2)
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elif s[i] == '#': inc(i)
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while true:
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case s[i]
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of '_': discard
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of '0'..'9':
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number = number shl 4 or (ord(s[i]) - ord('0'))
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foundDigit = true
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of 'a'..'f':
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number = number shl 4 or (ord(s[i]) - ord('a') + 10)
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foundDigit = true
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of 'A'..'F':
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number = number shl 4 or (ord(s[i]) - ord('A') + 10)
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foundDigit = true
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else: break
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inc(i)
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if foundDigit: result = i-start
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proc parseOct*(s: string, number: var int, start = 0): int {.
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rtl, extern: "npuParseOct", noSideEffect.} =
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## parses an octal number and stores its value in ``number``. Returns
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## the number of the parsed characters or 0 in case of an error.
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var i = start
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var foundDigit = false
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if s[i] == '0' and (s[i+1] == 'o' or s[i+1] == 'O'): inc(i, 2)
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while true:
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case s[i]
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of '_': discard
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of '0'..'7':
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number = number shl 3 or (ord(s[i]) - ord('0'))
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foundDigit = true
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else: break
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inc(i)
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if foundDigit: result = i-start
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proc parseIdent*(s: string, ident: var string, start = 0): int =
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## parses an identifier and stores it in ``ident``. Returns
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## the number of the parsed characters or 0 in case of an error.
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var i = start
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if s[i] in IdentStartChars:
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inc(i)
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while s[i] in IdentChars: inc(i)
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ident = substr(s, start, i-1)
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result = i-start
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proc parseIdent*(s: string, start = 0): string =
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## parses an identifier and stores it in ``ident``.
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## Returns the parsed identifier or an empty string in case of an error.
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result = ""
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var i = start
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if s[i] in IdentStartChars:
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inc(i)
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while s[i] in IdentChars: inc(i)
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result = substr(s, start, i-1)
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proc parseToken*(s: string, token: var string, validChars: set[char],
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start = 0): int {.inline, deprecated.} =
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## parses a token and stores it in ``token``. Returns
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## the number of the parsed characters or 0 in case of an error. A token
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## consists of the characters in `validChars`.
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##
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## **Deprecated since version 0.8.12**: Use ``parseWhile`` instead.
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var i = start
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while s[i] in validChars: inc(i)
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result = i-start
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token = substr(s, start, i-1)
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proc skipWhitespace*(s: string, start = 0): int {.inline.} =
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## skips the whitespace starting at ``s[start]``. Returns the number of
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## skipped characters.
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while s[start+result] in Whitespace: inc(result)
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proc skip*(s, token: string, start = 0): int {.inline.} =
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## skips the `token` starting at ``s[start]``. Returns the length of `token`
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## or 0 if there was no `token` at ``s[start]``.
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while result < token.len and s[result+start] == token[result]: inc(result)
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if result != token.len: result = 0
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proc skipIgnoreCase*(s, token: string, start = 0): int =
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## same as `skip` but case is ignored for token matching.
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while result < token.len and
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toLower(s[result+start]) == toLower(token[result]): inc(result)
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if result != token.len: result = 0
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proc skipUntil*(s: string, until: set[char], start = 0): int {.inline.} =
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## Skips all characters until one char from the set `until` is found
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## or the end is reached.
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## Returns number of characters skipped.
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while s[result+start] notin until and s[result+start] != '\0': inc(result)
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proc skipUntil*(s: string, until: char, start = 0): int {.inline.} =
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## Skips all characters until the char `until` is found
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## or the end is reached.
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## Returns number of characters skipped.
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while s[result+start] != until and s[result+start] != '\0': inc(result)
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proc skipWhile*(s: string, toSkip: set[char], start = 0): int {.inline.} =
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## Skips all characters while one char from the set `token` is found.
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## Returns number of characters skipped.
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while s[result+start] in toSkip and s[result+start] != '\0': inc(result)
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proc parseUntil*(s: string, token: var string, until: set[char],
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start = 0): int {.inline.} =
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## parses a token and stores it in ``token``. Returns
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## the number of the parsed characters or 0 in case of an error. A token
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## consists of the characters notin `until`.
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var i = start
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while i < s.len and s[i] notin until: inc(i)
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result = i-start
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token = substr(s, start, i-1)
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proc parseUntil*(s: string, token: var string, until: char,
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start = 0): int {.inline.} =
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## parses a token and stores it in ``token``. Returns
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## the number of the parsed characters or 0 in case of an error. A token
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## consists of any character that is not the `until` character.
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var i = start
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while i < s.len and s[i] != until: inc(i)
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result = i-start
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token = substr(s, start, i-1)
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proc parseWhile*(s: string, token: var string, validChars: set[char],
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start = 0): int {.inline.} =
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## parses a token and stores it in ``token``. Returns
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## the number of the parsed characters or 0 in case of an error. A token
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## consists of the characters in `validChars`.
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var i = start
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while s[i] in validChars: inc(i)
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result = i-start
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token = substr(s, start, i-1)
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proc captureBetween*(s: string, first: char, second = '\0', start = 0): string =
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## Finds the first occurence of ``first``, then returns everything from there
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## up to ``second``(if ``second`` is '\0', then ``first`` is used).
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var i = skipUntil(s, first, start)+1+start
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result = ""
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discard s.parseUntil(result, if second == '\0': first else: second, i)
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{.push overflowChecks: on.}
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# this must be compiled with overflow checking turned on:
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proc rawParseInt(s: string, b: var BiggestInt, start = 0): int =
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var
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sign: BiggestInt = -1
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i = start
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if s[i] == '+': inc(i)
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elif s[i] == '-':
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inc(i)
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sign = 1
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if s[i] in {'0'..'9'}:
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b = 0
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while s[i] in {'0'..'9'}:
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b = b * 10 - (ord(s[i]) - ord('0'))
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inc(i)
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while s[i] == '_': inc(i) # underscores are allowed and ignored
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b = b * sign
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result = i - start
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{.pop.} # overflowChecks
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proc parseBiggestInt*(s: string, number: var BiggestInt, start = 0): int {.
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rtl, extern: "npuParseBiggestInt", noSideEffect.} =
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## parses an integer starting at `start` and stores the value into `number`.
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## Result is the number of processed chars or 0 if there is no integer.
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## `EOverflow` is raised if an overflow occurs.
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var res: BiggestInt
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# use 'res' for exception safety (don't write to 'number' in case of an
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# overflow exception:
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result = rawParseInt(s, res, start)
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number = res
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proc parseInt*(s: string, number: var int, start = 0): int {.
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rtl, extern: "npuParseInt", noSideEffect.} =
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## parses an integer starting at `start` and stores the value into `number`.
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## Result is the number of processed chars or 0 if there is no integer.
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## `EOverflow` is raised if an overflow occurs.
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var res: BiggestInt
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result = parseBiggestInt(s, res, start)
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if (sizeof(int) <= 4) and
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((res < low(int)) or (res > high(int))):
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raise newException(EOverflow, "overflow")
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else:
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number = int(res)
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proc tenToThePowerOf(b: int): BiggestFloat =
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var b = b
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var a = 10.0
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result = 1.0
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while true:
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if (b and 1) == 1:
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result *= a
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b = b shr 1
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if b == 0: break
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a *= a
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proc parseBiggestFloat*(s: string, number: var BiggestFloat, start = 0): int {.
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rtl, extern: "npuParseBiggestFloat", noSideEffect.} =
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## parses a float starting at `start` and stores the value into `number`.
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## Result is the number of processed chars or 0 if there occured a parsing
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## error.
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var
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esign = 1.0
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sign = 1.0
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i = start
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exponent: int
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flags: int
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number = 0.0
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if s[i] == '+': inc(i)
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elif s[i] == '-':
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sign = -1.0
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inc(i)
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if s[i] == 'N' or s[i] == 'n':
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if s[i+1] == 'A' or s[i+1] == 'a':
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if s[i+2] == 'N' or s[i+2] == 'n':
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if s[i+3] notin IdentChars:
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number = NaN
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return i+3 - start
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return 0
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if s[i] == 'I' or s[i] == 'i':
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if s[i+1] == 'N' or s[i+1] == 'n':
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if s[i+2] == 'F' or s[i+2] == 'f':
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if s[i+3] notin IdentChars:
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number = Inf*sign
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return i+3 - start
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return 0
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while s[i] in {'0'..'9'}:
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# Read integer part
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flags = flags or 1
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number = number * 10.0 + toFloat(ord(s[i]) - ord('0'))
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inc(i)
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while s[i] == '_': inc(i)
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# Decimal?
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if s[i] == '.':
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var hd = 1.0
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inc(i)
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while s[i] in {'0'..'9'}:
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# Read fractional part
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flags = flags or 2
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number = number * 10.0 + toFloat(ord(s[i]) - ord('0'))
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hd = hd * 10.0
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inc(i)
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while s[i] == '_': inc(i)
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number = number / hd # this complicated way preserves precision
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# Again, read integer and fractional part
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if flags == 0: return 0
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# Exponent?
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if s[i] in {'e', 'E'}:
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inc(i)
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if s[i] == '+':
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inc(i)
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elif s[i] == '-':
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esign = -1.0
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inc(i)
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if s[i] notin {'0'..'9'}:
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return 0
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while s[i] in {'0'..'9'}:
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exponent = exponent * 10 + ord(s[i]) - ord('0')
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inc(i)
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while s[i] == '_': inc(i)
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# Calculate Exponent
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let hd = tenToThePowerOf(exponent)
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if esign > 0.0: number = number * hd
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else: number = number / hd
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# evaluate sign
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number = number * sign
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result = i - start
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proc parseFloat*(s: string, number: var float, start = 0): int {.
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rtl, extern: "npuParseFloat", noSideEffect.} =
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## parses a float starting at `start` and stores the value into `number`.
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## Result is the number of processed chars or 0 if there occured a parsing
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## error.
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var bf: BiggestFloat
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result = parseBiggestFloat(s, bf, start)
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number = bf
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type
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TInterpolatedKind* = enum ## describes for `interpolatedFragments`
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## which part of the interpolated string is
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## yielded; for example in "str$$$var${expr}"
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ikStr, ## ``str`` part of the interpolated string
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ikDollar, ## escaped ``$`` part of the interpolated string
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ikVar, ## ``var`` part of the interpolated string
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ikExpr ## ``expr`` part of the interpolated string
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iterator interpolatedFragments*(s: string): tuple[kind: TInterpolatedKind,
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value: string] =
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## Tokenizes the string `s` into substrings for interpolation purposes.
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##
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## Example:
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##
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## .. code-block:: nimrod
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## for k, v in interpolatedFragments(" $this is ${an example} $$"):
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## echo "(", k, ", \"", v, "\")"
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##
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## Results in:
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##
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## .. code-block:: nimrod
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## (ikString, " ")
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## (ikExpr, "this")
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## (ikString, " is ")
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## (ikExpr, "an example")
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## (ikString, " ")
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## (ikDollar, "$")
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var i = 0
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var kind: TInterpolatedKind
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while true:
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var j = i
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if s[j] == '$':
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if s[j+1] == '{':
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inc j, 2
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var nesting = 0
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while true:
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case s[j]
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of '{': inc nesting
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of '}':
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if nesting == 0:
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inc j
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break
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dec nesting
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of '\0':
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raise newException(EInvalidValue,
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"Expected closing '}': " & s[i..s.len])
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else: nil
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inc j
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inc i, 2 # skip ${
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kind = ikExpr
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elif s[j+1] in IdentStartChars:
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inc j, 2
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while s[j] in IdentChars: inc(j)
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inc i # skip $
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kind = ikVar
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elif s[j+1] == '$':
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inc j, 2
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inc i # skip $
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kind = ikDollar
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else:
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raise newException(EInvalidValue,
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"Unable to parse a varible name at " & s[i..s.len])
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else:
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while j < s.len and s[j] != '$': inc j
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kind = ikStr
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if j > i:
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# do not copy the trailing } for ikExpr:
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yield (kind, substr(s, i, j-1-ord(kind == ikExpr)))
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else:
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break
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i = j
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when isMainModule:
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for k, v in interpolatedFragments("$test{} $this is ${an{ example}} "):
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echo "(", k, ", \"", v, "\")"
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var value = 0
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discard parseHex("0x38", value)
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assert value == 56
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discard parseHex("0x34", value)
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assert value == 56 * 256 + 52
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value = -1
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discard parseHex("0x38", value)
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assert value == -200
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{.pop.}
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