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#
#
# Nimrod's Runtime Library
# (c) Copyright 2011 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## The ``strtabs`` module implements an efficient hash table that is a mapping
## from strings to strings. Supports a case-sensitive, case-insensitive and
## style-insensitive mode. An efficient string substitution operator ``%``
## for the string table is also provided.
import
os, hashes, strutils
include "system/inclrtl"
type
TStringTableMode* = enum ## describes the tables operation mode
modeCaseSensitive, ## the table is case sensitive
modeCaseInsensitive, ## the table is case insensitive
modeStyleInsensitive ## the table is style insensitive
TKeyValuePair = tuple[key, val: string]
TKeyValuePairSeq = seq[TKeyValuePair]
TStringTable* = object of TObject
counter: int
data: TKeyValuePairSeq
mode: TStringTableMode
PStringTable* = ref TStringTable ## use this type to declare string tables
proc len*(t: PStringTable): int {.rtl, extern: "nst$1".} =
## returns the number of keys in `t`.
result = t.counter
iterator pairs*(t: PStringTable): tuple[key, value: string] =
## iterates over any (key, value) pair in the table `t`.
for h in 0..high(t.data):
if not isNil(t.data[h].key):
yield (t.data[h].key, t.data[h].val)
type
TFormatFlag* = enum ## flags for the `%` operator
useEnvironment, ## use environment variable if the ``$key``
## is not found in the table
useEmpty, ## use the empty string as a default, thus it
## won't throw an exception if ``$key`` is not
## in the table
useKey ## do not replace ``$key`` if it is not found
## in the table (or in the environment)
# implementation
const
growthFactor = 2
startSize = 64
proc myhash(t: PStringTable, key: string): THash =
case t.mode
of modeCaseSensitive: result = hashes.hash(key)
of modeCaseInsensitive: result = hashes.hashIgnoreCase(key)
of modeStyleInsensitive: result = hashes.hashIgnoreStyle(key)
proc myCmp(t: PStringTable, a, b: string): bool =
case t.mode
of modeCaseSensitive: result = cmp(a, b) == 0
of modeCaseInsensitive: result = cmpIgnoreCase(a, b) == 0
of modeStyleInsensitive: result = cmpIgnoreStyle(a, b) == 0
proc mustRehash(length, counter: int): bool =
assert(length > counter)
result = (length * 2 < counter * 3) or (length - counter < 4)
proc nextTry(h, maxHash: THash): THash {.inline.} =
result = ((5 * h) + 1) and maxHash
proc RawGet(t: PStringTable, key: string): int =
var h: THash = myhash(t, key) and high(t.data) # start with real hash value
while not isNil(t.data[h].key):
if mycmp(t, t.data[h].key, key):
return h
h = nextTry(h, high(t.data))
result = - 1
proc `[]`*(t: PStringTable, key: string): string {.rtl, extern: "nstGet".} =
## retrieves the value at ``t[key]``. If `key` is not in `t`, "" is returned
## and no exception is raised. One can check with ``hasKey`` whether the key
## exists.
var index = RawGet(t, key)
if index >= 0: result = t.data[index].val
else: result = ""
proc hasKey*(t: PStringTable, key: string): bool {.rtl, extern: "nst$1".} =
## returns true iff `key` is in the table `t`.
result = rawGet(t, key) >= 0
proc RawInsert(t: PStringTable, data: var TKeyValuePairSeq, key, val: string) =
var h: THash = myhash(t, key) and high(data)
while not isNil(data[h].key):
h = nextTry(h, high(data))
data[h].key = key
data[h].val = val
proc Enlarge(t: PStringTable) =
var n: TKeyValuePairSeq
newSeq(n, len(t.data) * growthFactor)
for i in countup(0, high(t.data)):
if not isNil(t.data[i].key): RawInsert(t, n, t.data[i].key, t.data[i].val)
swap(t.data, n)
proc `[]=`*(t: PStringTable, key, val: string) {.rtl, extern: "nstPut".} =
## puts a (key, value)-pair into `t`.
var index = RawGet(t, key)
if index >= 0:
t.data[index].val = val
else:
if mustRehash(len(t.data), t.counter): Enlarge(t)
RawInsert(t, t.data, key, val)
inc(t.counter)
proc RaiseFormatException(s: string) =
var e: ref EInvalidValue
new(e)
e.msg = "format string: key not found: " & s
raise e
proc getValue(t: PStringTable, flags: set[TFormatFlag], key: string): string =
if hasKey(t, key): return t[key]
if useEnvironment in flags: result = os.getEnv(key)
else: result = ""
if result.len == 0:
if useKey in flags: result = '$' & key
elif not (useEmpty in flags): raiseFormatException(key)
proc newStringTable*(mode: TStringTableMode): PStringTable {.
rtl, extern: "nst$1".} =
## creates a new string table that is empty.
new(result)
result.mode = mode
result.counter = 0
newSeq(result.data, startSize)
proc newStringTable*(keyValuePairs: openarray[string],
mode: TStringTableMode): PStringTable {.
rtl, extern: "nst$1WithPairs".} =
## creates a new string table with given key value pairs.
## Example::
## var mytab = newStringTable("key1", "val1", "key2", "val2",
## modeCaseInsensitive)
result = newStringTable(mode)
var i = 0
while i < high(keyValuePairs):
result[keyValuePairs[i]] = keyValuePairs[i + 1]
inc(i, 2)
proc newStringTable*(keyValuePairs: openarray[tuple[key, val: string]],
mode: TStringTableMode = modeCaseSensitive): PStringTable {.
rtl, extern: "nst$1WithTableConstr".} =
## creates a new string table with given key value pairs.
## Example::
## var mytab = newStringTable({"key1": "val1", "key2": "val2"},
## modeCaseInsensitive)
result = newStringTable(mode)
for key, val in items(keyvaluePairs): result[key] = val
proc `%`*(f: string, t: PStringTable, flags: set[TFormatFlag] = {}): string {.
rtl, extern: "nstFormat".} =
## The `%` operator for string tables.
const
PatternChars = {'a'..'z', 'A'..'Z', '0'..'9', '_', '\x80'..'\xFF'}
result = ""
var i = 0
while i < len(f):
if f[i] == '$':
case f[i+1]
of '$':
add(result, '$')
inc(i, 2)
of '{':
var j = i + 1
while j < f.len and f[j] != '}': inc(j)
add(result, getValue(t, flags, substr(f, i+2, j-1)))
i = j + 1
of 'a'..'z', 'A'..'Z', '\x80'..'\xFF', '_':
var j = i + 1
while j < f.len and f[j] in PatternChars: inc(j)
add(result, getValue(t, flags, substr(f, i+1, j-1)))
i = j
else:
add(result, f[i])
inc(i)
else:
add(result, f[i])
inc(i)
proc `$`*(t: PStringTable): string {.rtl, extern: "nstDollar".} =
## The `$` operator for string tables.
if t.len == 0:
result = "{:}"
else:
result = "{"
for key, val in pairs(t):
if result.len > 1: result.add(", ")
result.add(key)
result.add(": ")
result.add(val)
result.add("}")
when isMainModule:
const x = {"k": "v", "11": "22", "565": "67"}.newStringTable
assert x["k"] == "v"
assert x["11"] == "22"
assert x["565"] == "67"
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