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docs/source/Components/FuncParser.md
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@ -1,16 +1,12 @@
# The Inline Function Parser
```
```
The [FuncParser](api:evennia.utils.funcparser#evennia.utils.funcparser.FuncParser) extracts and executes
The [FuncParser](evennia.utils.funcparser.FuncParser) extracts and executes
'inline functions'
embedded in a string on the form `$funcname(args, kwargs)`. Under the hood, this will
lead to a call to a Python function you control. The inline function call will be replaced by
embedded in a string on the form `$funcname(args, kwargs)`. Under the hood, this will
lead to a call to a Python function you control. The inline function call will be replaced by
the return from the function.
```python
```python
from evennia.utils.funcparser import FuncParser
def _power_callable(*args, **kwargs):
@ -48,72 +44,72 @@ parser.parse("This is an escaped $$pow(4) and so is this \$pow(3)")
The FuncParser can be applied to any string. Out of the box it's applied in a few situations:
- _Outgoing messages_. All messages sent from the server is processed through FuncParser and every
callable is provided the [Session](./Sessions) of the object receiving the message. This potentially
callable is provided the [Session](./Sessions.md) of the object receiving the message. This potentially
allows a message to be modified on the fly to look different for different recipients.
- _Prototype values_. A [Prototype](./Prototypes) dict's values are run through the parser such that every
- _Prototype values_. A [Prototype](./Prototypes.md) dict's values are run through the parser such that every
callable gets a reference to the rest of the prototype. In the Prototype ORM, this would allow builders
to safely call functions to set non-string values to prototype values, get random values, reference
other fields of the prototype, and more.
- _Actor-stance in messages to others_. In the
[Object.msg_contents](api:evennia.objects.objects#DefaultObject.msg_contents) method,
[Object.msg_contents](evennia.objects.objects.DefaultObject.msg_contents) method,
the outgoing string is parsed for special `$You()` and `$conj()` callables to decide if a given recipient
should see "You" or the character's name.
```important::
```{important}
The inline-function parser is not intended as a 'softcode' programming language. It does not
have things like loops and conditionals, for example. While you could in principle extend it to
do very advanced things and allow builders a lot of power, all-out coding is something
have things like loops and conditionals, for example. While you could in principle extend it to
do very advanced things and allow builders a lot of power, all-out coding is something
Evennia expects you to do in a proper text editor, outside of the game, not from inside it.
```
## Using the FuncParser
You can apply inline function parsing to any string. The
[FuncParser](api:evennia.utils.funcparser.FuncParser) is imported as `evennia.utils.funcparser`.
## Using the FuncParser
You can apply inline function parsing to any string. The
[FuncParser](evennia.utils.funcparser.FuncParser) is imported as `evennia.utils.funcparser`.
```python
from evennia.utils import funcparser
parser = FuncParser(callables, **default_kwargs)
parsed_string = parser.parser(input_string, raise_errors=False,
escape=False, strip=False,
parsed_string = parser.parser(input_string, raise_errors=False,
escape=False, strip=False,
return_str=True, **reserved_kwargs)
# callables can also be passed as paths to modules
parser = FuncParser(["game.myfuncparser_callables", "game.more_funcparser_callables"])
```
Here, `callables` points to a collection of normal Python functions (see next section) for you to make
Here, `callables` points to a collection of normal Python functions (see next section) for you to make
available to the parser as you parse strings with it. It can either be
- A `dict` of `{"functionname": callable, ...}`. This allows you do pick and choose exactly which callables
to include and how they should be named. Do you want a callable to be available under more than one name?
Just add it multiple times to the dict, with a different key.
- A `module` or (more commonly) a `python-path` to a module. This module can define a dict
- A `module` or (more commonly) a `python-path` to a module. This module can define a dict
`FUNCPARSER_CALLABLES = {"funcname": callable, ...}` - this will be imported and used like the `dict` above.
If no such variable is defined, _every_ top-level function in the module (whose name doesn't start with
an underscore `_`) will be considered a suitable callable. The name of the function will be the `$funcname`
If no such variable is defined, _every_ top-level function in the module (whose name doesn't start with
an underscore `_`) will be considered a suitable callable. The name of the function will be the `$funcname`
by which it can be called.
- A `list` of modules/paths. This allows you to pull in modules from many sources for your parsing.
The other arguments to the parser:
- `raise_errors` - By default, any errors from a callable will be quietly ignored and the result
will be that the failing function call will show verbatim. If `raise_errors` is set,
then parsing will stop and whatever exception happened will be raised. It'd be up to you to handle
- `raise_errors` - By default, any errors from a callable will be quietly ignored and the result
will be that the failing function call will show verbatim. If `raise_errors` is set,
then parsing will stop and whatever exception happened will be raised. It'd be up to you to handle
this properly.
- `escape` - Returns a string where every `$func(...)` has been escaped as `\$func()`.
- `strip` - Remove all `$func(...)` calls from string (as if each returned `''`).
- `return_str` - When `True` (default), `parser` always returns a string. If `False`, it may return
the return value of a single function call in the string. This is the same as using the `.parse_to_any`
- `return_str` - When `True` (default), `parser` always returns a string. If `False`, it may return
the return value of a single function call in the string. This is the same as using the `.parse_to_any`
method.
- The `**default/reserved_keywords` are optional and allow you to pass custom data into _every_ function
call. This is great for including things like the current session or config options. Defaults can be
replaced if the user gives the same-named kwarg in the string's function call. Reserved kwargs are always passed,
ignoring defaults or what the user passed. In addition, the `funcparser` and `raise_errors`
ignoring defaults or what the user passed. In addition, the `funcparser` and `raise_errors`
reserved kwargs are always passed - the first is a back-reference to the `FuncParser` instance and the second
is the `raise_errors` boolean passed into `FuncParser.parse`.
Here's an example of using the default/reserved keywords:
Here's an example of using the default/reserved keywords:
```python
def _test(*args, **kwargs):
@ -123,15 +119,15 @@ def _test(*args, **kwargs):
parser = funcparser.FuncParser({"test": _test}, mydefault=2)
result = parser.parse("$test(foo, bar=4)", myreserved=[1, 2, 3])
```
Here the callable will be called as
Here the callable will be called as
```python
_test('foo', bar='4', mydefault=2, myreserved=[1, 2, 3],
funcparser=<FuncParser>, raise_errors=False)
_test('foo', bar='4', mydefault=2, myreserved=[1, 2, 3],
funcparser=<FuncParser>, raise_errors=False)
```
The `mydefault=2` kwarg could be overwritten if we made the call as `$test(mydefault=...)`
but `myreserved=[1, 2, 3]` will _always_ be sent as-is and will override a call `$test(myreserved=...)`.
The `mydefault=2` kwarg could be overwritten if we made the call as `$test(mydefault=...)`
but `myreserved=[1, 2, 3]` will _always_ be sent as-is and will override a call `$test(myreserved=...)`.
The `funcparser`/`raise_errors` kwargs are also always included as reserved kwargs.
## Defining custom callables
@ -144,44 +140,44 @@ def funcname(*args, **kwargs):
return something
```
> The `*args` and `**kwargs` must always be included. If you are unsure how `*args` and `**kwargs` work in Python,
> The `*args` and `**kwargs` must always be included. If you are unsure how `*args` and `**kwargs` work in Python,
> [read about them here](https://www.digitalocean.com/community/tutorials/how-to-use-args-and-kwargs-in-python-3).
The input from the innermost `$funcname(...)` call in your callable will always be a `str`. Here's
The input from the innermost `$funcname(...)` call in your callable will always be a `str`. Here's
an example of an `$toint` function; it converts numbers to integers.
"There's a $toint(22.0)% chance of survival."
What will enter the `$toint` callable (as `args[0]`) is the _string_ `"22.0"`. The function is responsible
for converting this to a number so that we can convert it to an integer. We must also properly handle invalid
for converting this to a number so that we can convert it to an integer. We must also properly handle invalid
inputs (like non-numbers).
If you want to mark an error, raise `evennia.utils.funcparser.ParsingError`. This stops the entire parsing
of the string and may or may not raise the exception depending on what you set `raise_errors` to when you
of the string and may or may not raise the exception depending on what you set `raise_errors` to when you
created the parser.
However, if you _nest_ functions, the return of the innermost function may be something other than
a string. Let's introduce the `$eval` function, which evaluates simple expressions using
However, if you _nest_ functions, the return of the innermost function may be something other than
a string. Let's introduce the `$eval` function, which evaluates simple expressions using
Python's `literal_eval` and/or `simple_eval`.
"There's a $toint($eval(10 * 2.2))% chance of survival."
"There's a $toint($eval(10 * 2.2))% chance of survival."
Since the `$eval` is the innermost call, it will get a string as input - the string `"10 * 2.2"`.
It evaluates this and returns the `float` `22.0`. This time the outermost `$toint` will be called with
this `float` instead of with a string.
Since the `$eval` is the innermost call, it will get a string as input - the string `"10 * 2.2"`.
It evaluates this and returns the `float` `22.0`. This time the outermost `$toint` will be called with
this `float` instead of with a string.
> It's important to safely validate your inputs since users may end up nesting your callables in any order.
> It's important to safely validate your inputs since users may end up nesting your callables in any order.
> See the next section for useful tools to help with this.
In these examples, the result will be embedded in the larger string, so the result of the entire parsing
will be a string:
In these examples, the result will be embedded in the larger string, so the result of the entire parsing
will be a string:
```python
parser.parse(above_string)
"There's a 22% chance of survival."
```
However, if you use the `parse_to_any` (or `parse(..., return_str=True)`) and _don't add any extra string around the outermost function call_,
However, if you use the `parse_to_any` (or `parse(..., return_str=True)`) and _don't add any extra string around the outermost function call_,
you'll get the return type of the outermost callable back:
```python
@ -194,13 +190,13 @@ parser.parse_to_any("$toint($eval(10 * 2.2)")
### Safe convertion of inputs
Since you don't know in which order users may use your callables, they should always check the types
of its inputs and convert to the type the callable needs. Note also that when converting from strings,
there are limits what inputs you can support. This is because FunctionParser strings are often used by
non-developer players/builders and some things (such as complex classes/callables etc) are just not
of its inputs and convert to the type the callable needs. Note also that when converting from strings,
there are limits what inputs you can support. This is because FunctionParser strings are often used by
non-developer players/builders and some things (such as complex classes/callables etc) are just not
safe/possible to convert from string representation.
In `evennia.utils.utils` is a helper called
[safe_convert_to_types](api:evennia.utils.utils#evennia.utils.utils.safe_convert_to_types). This function
In `evennia.utils.utils` is a helper called
[safe_convert_to_types](evennia.utils.utils.safe_convert_to_types). This function
automates the conversion of simple data types in a safe way:
```python
@ -208,94 +204,94 @@ from evennia.utils.utils import safe_convert_to_types
def _process_callable(*args, **kwargs):
"""
A callable with a lot of custom options
$process(expression, local, extra=34, extra2=foo)
A callable with a lot of custom options
$process(expression, local, extra=34, extra2=foo)
"""
args, kwargs = safe_convert_to_type(
(('py', 'py'), {'extra1': int, 'extra2': str}),
(('py', 'py'), {'extra1': int, 'extra2': str}),
*args, **kwargs)
# args/kwargs should be correct types now
# args/kwargs should be correct types now
```
In other words,
```python
```python
args, kwargs = safe_convert_to_type(
(tuple_of_arg_converters, dict_of_kwarg_converters), *args, **kwargs)
```
Each converter should be a callable taking one argument - this will be the arg/kwarg-value to convert. The
special converter `"py"` will try to convert a string argument to a Python structure with the help of the
following tools (which you may also find useful to experiment with on your own):
Each converter should be a callable taking one argument - this will be the arg/kwarg-value to convert. The
special converter `"py"` will try to convert a string argument to a Python structure with the help of the
following tools (which you may also find useful to experiment with on your own):
- [ast.literal_eval](https://docs.python.org/3.8/library/ast.html#ast.literal_eval) is an in-built Python
function. It
_only_ supports strings, bytes, numbers, tuples, lists, dicts, sets, booleans and `None`. That's
it - no arithmetic or modifications of data is allowed. This is good for converting individual values and
lists/dicts from the input line to real Python objects.
- [simpleeval](https://pypi.org/project/simpleeval/) is a third-party tool included with Evennia. This
allows for evaluation of simple (and thus safe) expressions. One can operate on numbers and strings
with +-/* as well as do simple comparisons like `4 > 3` and more. It does _not_ accept more complex
- [simpleeval](https://pypi.org/project/simpleeval/) is a third-party tool included with Evennia. This
allows for evaluation of simple (and thus safe) expressions. One can operate on numbers and strings
with `+-/*` as well as do simple comparisons like `4 > 3` and more. It does _not_ accept more complex
containers like lists/dicts etc, so this and `literal_eval` are complementary to each other.
```warning::
It may be tempting to run use Python's in-built ``eval()`` or ``exec()`` functions as converters since
these are able to convert any valid Python source code to Python. NEVER DO THIS unless you really, really
know that ONLY developers will ever modify the string going into the callable. The parser is intended
for untrusted users (if you were trusted you'd have access to Python already). Letting untrusted users
pass strings to ``eval``/``exec`` is a MAJOR security risk. It allows the caller to run arbitrary
Python code on your server. This is the path to maliciously deleted hard drives. Just don't do it and
```{warning}
It may be tempting to run use Python's in-built ``eval()`` or ``exec()`` functions as converters since
these are able to convert any valid Python source code to Python. NEVER DO THIS unless you really, really
know that ONLY developers will ever modify the string going into the callable. The parser is intended
for untrusted users (if you were trusted you'd have access to Python already). Letting untrusted users
pass strings to ``eval``/``exec`` is a MAJOR security risk. It allows the caller to run arbitrary
Python code on your server. This is the path to maliciously deleted hard drives. Just don't do it and
sleep better at night.
```
## Default callables
These are some example callables you can import and add your parser. They are divided into
global-level dicts in `evennia.utils.funcparser`. Just import the dict(s) and merge/add one or
These are some example callables you can import and add your parser. They are divided into
global-level dicts in `evennia.utils.funcparser`. Just import the dict(s) and merge/add one or
more to them when you create your `FuncParser` instance to have those callables be available.
### `evennia.utils.funcparser.FUNCPARSER_CALLABLES`
These are the 'base' callables.
- `$eval(expression)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_eval)) -
this uses `literal_eval` and `simple_eval` (see previous section) attemt to convert a string expression
- `$eval(expression)` ([code](evennia.utils.funcparser.funcparser_callable_eval)) -
this uses `literal_eval` and `simple_eval` (see previous section) attemt to convert a string expression
to a python object. This handles e.g. lists of literals `[1, 2, 3]` and simple expressions like `"1 + 2"`.
- `$toint(number)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_toint)) -
- `$toint(number)` ([code](evennia.utils.funcparser.funcparser_callable_toint)) -
always converts an output to an integer, if possible.
- `$add/sub/mult/div(obj1, obj2)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_add)) -
this adds/subtracts/multiplies and divides to elements together. While simple addition could be done with
`$eval`, this could for example be used also to add two lists together, which is not possible with `eval`;
- `$add/sub/mult/div(obj1, obj2)` ([code](evennia.utils.funcparser.funcparser_callable_add)) -
this adds/subtracts/multiplies and divides to elements together. While simple addition could be done with
`$eval`, this could for example be used also to add two lists together, which is not possible with `eval`;
for example `$add($eval([1,2,3]), $eval([4,5,6])) -> [1, 2, 3, 4, 5, 6]`.
- `$round(float, significant)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_round)) -
- `$round(float, significant)` ([code](evennia.utils.funcparser.funcparser_callable_round)) -
rounds an input float into the number of provided significant digits. For example `$round(3.54343, 3) -> 3.543`.
- `$random([start, [end]])` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_random)) -
this works like the Python `random()` function, but will randomize to an integer value if both start/end are
- `$random([start, [end]])` ([code](evennia.utils.funcparser.funcparser_callable_random)) -
this works like the Python `random()` function, but will randomize to an integer value if both start/end are
integers. Without argument, will return a float between 0 and 1.
- `$randint([start, [end]])` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_randint)) -
- `$randint([start, [end]])` ([code](evennia.utils.funcparser.funcparser_callable_randint)) -
works like the `randint()` python function and always returns an integer.
- `$choice(list)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_choice)) -
the input will automatically be parsed the same way as `$eval` and is expected to be an iterable. A random
- `$choice(list)` ([code](evennia.utils.funcparser.funcparser_callable_choice)) -
the input will automatically be parsed the same way as `$eval` and is expected to be an iterable. A random
element of this list will be returned.
- `$pad(text[, width, align, fillchar])` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_pad)) -
- `$pad(text[, width, align, fillchar])` ([code](evennia.utils.funcparser.funcparser_callable_pad)) -
this will pad content. `$pad("Hello", 30, c, -)` will lead to a text centered in a 30-wide block surrounded by `-`
characters.
- `$crop(text, width=78, suffix='[...]')` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_crop)) -
- `$crop(text, width=78, suffix='[...]')` ([code](evennia.utils.funcparser.funcparser_callable_crop)) -
this will crop a text longer than the width, by default ending it with a `[...]`-suffix that also fits within
the width. If no width is given, the client width or `settings.DEFAULT_CLIENT_WIDTH` will be used.
- `$space(num)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_space)) -
- `$space(num)` ([code](evennia.utils.funcparser.funcparser_callable_space)) -
this will insert `num` spaces.
- `$just(string, width=40, align=c, indent=2)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_justify)) -
- `$just(string, width=40, align=c, indent=2)` ([code](evennia.utils.funcparser.funcparser_callable_justify)) -
justifies the text to a given width, aligning it left/right/center or 'f' for full (spread text across width).
- `$ljust` - shortcut to justify-left. Takes all other kwarg of `$just`.
- `$rjust` - shortcut to right justify.
- `$cjust` - shortcut to center justify.
- `$clr(startcolor, text[, endcolor])` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_clr)) -
color text. The color is given with one or two characters without the preceeding `|`. If no endcolor is
- `$clr(startcolor, text[, endcolor])` ([code](evennia.utils.funcparser.funcparser_callable_clr)) -
color text. The color is given with one or two characters without the preceeding `|`. If no endcolor is
given, the string will go back to neutral, so `$clr(r, Hello)` is equivalent to `|rHello|n`.
### `evennia.utils.funcparser.SEARCHING_CALLABLES`
@ -304,15 +300,16 @@ These are callables that requires access-checks in order to search for objects.
extra reserved kwargs to be passed when running the parser:
```python
parser.parse_to_any(string, caller=<object or account>, access="control", ...)`
parser.parse_to_any(string, caller=<object or account>, access="control", ...)
```
The `caller` is required, it's the the object to do the access-check for. The `access` kwarg is the
[lock type](./Locks) to check, default being `"control"`.
The `caller` is required, it's the the object to do the access-check for. The `access` kwarg is the
[lock type](./Locks.md) to check, default being `"control"`.
- `$search(query,type=account|script,return_list=False)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_search)) -
this will look up and try to match an object by key or alias. Use the `type` kwarg to
search for `account` or `script` instead. By default this will return nothing if there are more than one
- `$search(query,type=account|script,return_list=False)` ([code](evennia.utils.funcparser.funcparser_callable_search)) -
this will look up and try to match an object by key or alias. Use the `type` kwarg to
search for `account` or `script` instead. By default this will return nothing if there are more than one
match; if `return_list` is `True` a list of 0, 1 or more matches will be returned instead.
- `$obj(query)`, `$dbref(query)` - legacy aliases for `$search`.
- `$objlist(query)` - legacy alias for `$search`, always returning a list.
@ -320,9 +317,9 @@ The `caller` is required, it's the the object to do the access-check for. The `a
### `evennia.utils.funcparser.ACTOR_STANCE_CALLABLES`
These are used to implement actor-stance emoting. They are used by the
[DefaultObject.msg_contents](api:evennia.objects.objects#evennia.objects.objects.DefaultObject.msg_contents) method
by default.
These are used to implement actor-stance emoting. They are used by the
[DefaultObject.msg_contents](evennia.objects.objects.DefaultObject.msg_contents) method
by default.
These all require extra kwargs be passed into the parser:
@ -333,16 +330,16 @@ parser.parse(string, caller=<obj>, receiver=<obj>, mapping={'key': <obj>, ...})
Here the `caller` is the one sending the message and `receiver` the one to see it. The `mapping` contains
references to other objects accessible via these callables.
- `$you([key])` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_you)) -
if no `key` is given, this represents the `caller`, otherwise an object from `mapping`
will be used. As this message is sent to different recipients, the `receiver` will change and this will
be replaced either with the string `you` (if you and the receiver is the same entity) or with the
- `$you([key])` ([code](evennia.utils.funcparser.funcparser_callable_you)) -
if no `key` is given, this represents the `caller`, otherwise an object from `mapping`
will be used. As this message is sent to different recipients, the `receiver` will change and this will
be replaced either with the string `you` (if you and the receiver is the same entity) or with the
result of `you_obj.get_display_name(looker=receiver)`. This allows for a single string to echo differently
depending on who sees it, and also to reference other people in the same way.
- `$You([key])` - same as `$you` but always capitalized.
- `$conj(verb)` ([code](api:evennia.utils.funcparser#evennia.utils.funcparser.funcparser_callable_conjugate)) -- conjugates a verb between 4nd person presens to 3rd person presence depending on who
- `$conj(verb)` ([code](evennia.utils.funcparser.funcparser_callable_conjugate)) -- conjugates a verb between 4nd person presens to 3rd person presence depending on who
sees the string. For example `"$You() $conj(smiles)".` will show as "You smile." and "Tom smiles." depending
on who sees it. This makes use of the tools in [evennia.utils.verb_conjugation](api:evennia.utils.verb_conjugation)
on who sees it. This makes use of the tools in [evennia.utils.verb_conjugation](evennia.utils.verb_conjugation)
to do this, and only works for English verbs.
### Example
@ -377,10 +374,10 @@ result = parser.parse(string)
```
Above we define two callables `_dashline` and `_uptime` and map them to names `"dashline"` and `"uptime"`,
which is what we then can call as `$header` and `$uptime` in the string. We also have access to
which is what we then can call as `$header` and `$uptime` in the string. We also have access to
all the defaults (like `$toint()`).
The parsed result of the above would be something like this:
The parsed result of the above would be something like this:
This is the current uptime:
------- 343 seconds -------
------- 343 seconds -------