Hashtable Chilkat2 Perl Reference Documentation
Chilkat2::Hashtable
Current Version: 11.7.0
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Chilkat.Hashtable
Store values as strings or integers using straightforward add, replace,
and lookup methods.
Check whether a key exists and retrieve its value without manually
scanning a list or parsing text.
Maintain a mutable collection by adding new entries, replacing existing
values, removing individual keys, or clearing the table.
Retrieve the set of keys when application logic needs to loop through
the stored entries.
Import URL query parameters into the table and serialize the table back
to a query-string representation.
Save the hashtable to XML or reload it from XML when values need to be
persisted or transferred in a simple structured format.
For an extended overview, see
Hashtable Class Overview.
Store, look up, remove, enumerate, import, and serialize key/value pairs.
Chilkat.Hashtable provides a simple key/value collection for
storing string and integer values by key. It can add or replace entries,
look up values, test whether keys exist, remove entries, count items,
enumerate keys, import URL query parameters, serialize values back to a
query string, and save or load the table in XML format.
String and integer values
Fast key lookup
Add, replace, and remove
Enumerate keys
Query string helpers
XML persistence
Hashtable when application code needs a small mutable
key/value table, especially for lookup tables, parsed query parameters, or
simple string/integer settings. Add values with AddStr or
AddInt, retrieve them with LookupStr or
LookupInt, and use XML or query-string methods when the table
needs to be saved, loaded, or converted.
Object Creation
use Chilkat2;
my $hashtable = Chilkat2::Hashtable->new;
# or set properties (and RaiseError) at creation:
# my $hashtable = Chilkat2::Hashtable->new(VerboseLogging => 1, RaiseError => 1);Creates the object. The optional pairs set writable properties (and RaiseError) in order, as if set one by one; an unknown or read-only name croaks. use Chilkat2; loads every class; the Chilkat2/Hashtable.pm file holds only this class's documentation (perldoc Chilkat2::Hashtable).
Perl frees the object when its last reference goes (undef $hashtable, or the variable going out of scope); there is nothing to close. Objects returned by methods are independent and freed the same way. The class may be subclassed (use parent -norequire, 'Chilkat2::Hashtable';): an object is a blessed hash reference whose hash is free for the subclass's own fields.
When false (the default), a method that fails returns false (or undef), and the reason is in LastErrorText. When true, it dies with a Chilkat2::Error instead, as DBI does with its RaiseError. Objects returned by a method inherit the value of the object that returned them.
Errors
A Chilkat2::Error stringifies to the failed call's full LastErrorText, and has the methods text, class ('Chilkat2::Hashtable'), method (the method name) and object. Methods that look something up and find nothing return undef without dying (each such method says so), methods that answer a question (HasMember, IsUnlocked, ...) return a plain boolean, and property reads and writes never fail for Chilkat reasons.
Misuse always croaks, with your file and line, whatever RaiseError is: a wrong number of arguments, a reference or undef where a string or number is expected, an object of the wrong class, an out-of-range integer, a string containing a NUL character, a wide character in a byte string, or a write to a read-only property.
Strings are Perl character strings in both directions (length, regexes and :encoding layers see characters); binary data (BinData) is a byte string. Unlocking: call Chilkat2::Global->new->UnlockBundle('...') once at startup.
Properties
Count
my $intVal = $hashtable->Count;
The number of entries currently stored in the hashtable.
Each key contributes one entry regardless of whether its value is a string or an integer. Adding a new key increases Count; replacing the value of an existing key does not. Removing an entry decreases it, and Clear resets it to 0.
DebugLogFilePath
my $strVal = $hashtable->DebugLogFilePath;
$hashtable->DebugLogFilePath($strVal);
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastErrorHtml
my $strVal = $hashtable->LastErrorHtml;
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
my $strVal = $hashtable->LastErrorText;
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
my $strVal = $hashtable->LastErrorXml;
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
my $boolVal = $hashtable->LastMethodSuccess;
$hashtable->LastMethodSuccess($boolVal);
Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
VerboseLogging
my $boolVal = $hashtable->VerboseLogging;
$hashtable->VerboseLogging($boolVal);
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
my $strVal = $hashtable->Version;
Methods
AddFromXmlSb
# $success is true or false
my $success = $hashtable->AddFromXmlSb($sbXml);
Reads hashtable XML previously produced by ToXmlSb from the StringBuilder passed in $sbXml
The operation merges with the existing table: keys not present in the XML remain, and an imported entry replaces the current value for the same key. Call Clear first when the XML should completely replace the current contents.
Returns 1 when the XML is parsed and imported successfully; otherwise returns 0.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
AddInt
# $value is an integer
# $success is true or false
my $success = $hashtable->AddInt($key, $value);
Adds an entry whose string key is $key$value
Returns 1 when the entry is added or replaced. Returns 0 if the operation cannot be completed, such as because memory could not be allocated.
Count. Use LookupInt to retrieve an integer value.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
AddQueryParams
# $success is true or false
my $success = $hashtable->AddQueryParams($queryParams);
Parses URL query parameters from $queryParams
field1=value1&field2=value2&field3=value3
Each value is expected to be URL encoded and is URL decoded before being stored. If an imported key already exists, its previous value is replaced. Returns 1 on success and 0 if the query parameters cannot be imported.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
AddStr
# $value is a string
# $success is true or false
my $success = $hashtable->AddStr($key, $value);
Adds an entry whose string key is $key$value
Returns 1 when the entry is added or replaced. Returns 0 if the operation cannot be completed, such as because memory could not be allocated.
Count. Use LookupStr to retrieve a string value.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Clear
Removes every entry from the hashtable. After this call, Count is 0.
The current hash-table capacity is retained. To clear the entries and also select a different bucket capacity, call ClearWithNewCapacity.
Returns the object, so calls can be chained.
topClearWithNewCapacity
# $success is true or false
my $success = $hashtable->ClearWithNewCapacity($capacity);
Removes every entry and reinitializes the hashtable with $capacityHashtable object is 521.
Returns 1 on success and 0 if the table cannot be reinitialized.
| Term | Meaning |
|---|---|
Count | The number of stored entries. |
| Capacity | The number of hash buckets, not a maximum entry count. |
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Contains
# $flag is true or false
my $flag = $hashtable->Contains($key);
Returns 1 if the hashtable contains the string key $key0. The result tests key existence regardless of the value stored for that key.
Contains when a lookup result could be ambiguous. For example, LookupInt returns 0 both for a missing key and for an entry whose value is actually zero.Never dies: false is an answer, not a failure.
topContainsIntKey
# $flag is true or false
my $flag = $hashtable->ContainsIntKey($key);
Returns 1 if the hashtable contains the integer key $key0.
Contains, which tests for a string key, and from AddInt, whose key is a string and whose value is an integer.Never dies: false is an answer, not a failure.
topGetKeys
# $success is true or false
my $success = $hashtable->GetKeys($strTable);
Appends all hashtable key strings to the StringTable passed in $strTable$strTable
Returns 1 on success and 0 on failure.
StringTable first when it should contain only the current hashtable keys.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
LookupInt
# $n is an integer
my $n = $hashtable->LookupInt($key);
Returns the integer value associated with the string key $keyAddInt.
If the key does not exist, the return value is 0.
0 is also a valid stored value, call Contains first when the application must distinguish a missing key from an entry containing zero.LookupStr
# $str is a string or undef
my $str = $hashtable->LookupStr($key);
Returns the string value associated with the string key $keyAddStr or AddQueryParams.
null, Nothing, or an empty string. An empty string may also be a legitimate value. Use Contains or LastMethodSuccess when the distinction matters.Returns undef if not found: this is not an error, and it never dies, whatever RaiseError is.
Remove
# $flag is true or false
my $flag = $hashtable->Remove($key);
Removes the entry whose string key is $key
- Returns
1if the key existed and the entry was removed. - Returns
0if the key was not present.
A 0 result caused by an absent key is a normal lookup outcome, not an indication that the hashtable was damaged. Removing an existing entry decreases Count by one.
Never dies: false is an answer, not a failure.
topToQueryString
my $str = $hashtable->ToQueryString();
Serializes the hashtable as a URL query string in the following form:
key1=value1&key2=value2&key3=value3
Each value is URL encoded. The returned string does not include a leading ?.
LastMethodSuccess.Returns undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ToXmlSb
# $success is true or false
my $success = $hashtable->ToXmlSb($sbXml);
Serializes the current hashtable to Chilkat's hashtable XML format and appends the XML to the StringBuilder passed in $sbXmlStringBuilder is preserved.
Returns 1 on success and 0 on failure. The generated XML can be loaded by AddFromXmlSb.
<hashtable> <e><k>key</k><v>value</v></e> </hashtable>
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.