#
#
# The Nim Compiler
# (c) Copyright 2012 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# Identifier handling
# An identifier is a shared immutable string that can be compared by its
# id. This module is essential for the compiler's performance.
import
hashes, wordrecg
type
PIdent* = ref TIdent
TIdent*{.acyclic.} = object
id*: int # unique id; use this for comparisons and not the pointers
s*: string
next*: PIdent # for hash-table chaining
h*: Hash # hash value of s
IdentCache* = ref object
buckets: array[0..4096 * 2 - 1, PIdent]
wordCounter: int
idAnon*, idDelegator*, emptyIdent*: PIdent
proc resetIdentCache*() = discard
proc cmpIgnoreStyle*(a, b: cstring, blen: int): int =
if a[0] != b[0]: return 1
var i = 0
var j = 0
result = 1
while j < blen:
while a[i] == '_': inc(i)
while b[j] == '_': inc(j)
# tolower inlined:
var aa = a[i]
var bb = b[j]
if aa >= 'A' and aa <= 'Z': aa = chr(ord(aa) + (ord('a') - ord('A')))
if bb >= 'A' and bb <= 'Z': bb = chr(ord(bb) + (ord('a') - ord('A')))
result = ord(aa) - ord(bb)
if (result != 0) or (aa == '\0'): break
inc(i)
inc(j)
if result == 0:
if a[i] != '\0': result = 1
proc cmpExact(a, b: cstring, blen: int): int =
var i = 0
var j = 0
result = 1
while j < blen:
var aa = a[i]
var bb = b[j]
result = ord(aa) - ord(bb)
if (result != 0) or (aa == '\0'): break
inc(i)
inc(j)
if result == 0:
if a[i] != '\0': result = 1
proc getIdent*(ic: IdentCache; identifier: cstring, length: int, h: Hash): PIdent =
var idx = h and high(ic.buckets)
result = ic.buckets[idx]
var last: PIdent = nil
var id = 0
while result != nil:
if cmpExact(cstring(result.s), identifier, length) == 0:
if last != nil:
# make access to last looked up identifier faster:
last.next = result.next
result.next = ic.buckets[idx]
ic.buckets[idx] = result
return
elif cmpIgnoreStyle(cstring(result.s), identifier, length) == 0:
assert((id == 0) or (id == result.id))
id = result.id
last = result
result = result.next
new(result)
result.h = h
result.s = newString(length)
for i in 0..<length: result.s[i] = identifier[i]
result.next = ic.buckets[idx]
ic.buckets[idx] = result
if id == 0:
inc(ic.wordCounter)
result.id = -ic.wordCounter
else:
result.id = id
proc getIdent*(ic: IdentCache; identifier: string): PIdent =
result = getIdent(ic, cstring(identifier), identifier.len,
hashIgnoreStyle(identifier))
proc getIdent*(ic: IdentCache; identifier: string, h: Hash): PIdent =
result = getIdent(ic, cstring(identifier), identifier.len, h)
proc newIdentCache*(): IdentCache =
result = IdentCache()
result.idAnon = result.getIdent":anonymous"
result.wordCounter = 1
result.idDelegator = result.getIdent":delegator"
result.emptyIdent = result.getIdent("")
# initialize the keywords:
for s in succ(low(specialWords))..high(specialWords):
result.getIdent(specialWords[s], hashIgnoreStyle(specialWords[s])).id = ord(s)
proc whichKeyword*(id: PIdent): TSpecialWord =
if id.id < 0: result = wInvalid
else: result = TSpecialWord(id.id)