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= Option Syntax =

== Meaning of the call syntax documentation ==

All parameters can be specified by keyword or by position. 
Once a parameter is specified by keyword, the rest of the parameters must be specified by keyword too.
Some parameters have default values and are optional. These parameters are documented in the form `keyword = defaultvalue`.

Consider the following example:

{{{
name(p, qs, r, s=v1, t=Enum1)
}}}

 * `p` (type_p): some explanation
 * `qs` (list of type_q): some explanation
 * `r` (type_r): some explanation
 * `s` (type_s): some explanation
 * `t` (Enum): some explanation
  * Enum0: some explanation
  * Enum1: some explanation
  * Enum2: some explanation

Parameters `p`, `qs` and `r` are mandatory. 
`qs` is a list parameter. List parameters have to be enclosed in square brackets. 
For example, let `h1`, `h2`, `h3`
be heuristic specifications, then `[h1, h3]` and `[h2]` are examples for a 
list of heuristic specifications. 

Parameters `s` and `t` are optional.
`s` has the default value `v1` and `t` the default value `Enum1`. `t` is an enumeration parameter and can only take the values listed (here Enum0, Enum1, Enum2). 
These values may also be passed by number, e.g. here `t=Enum1` and `t=1` are equivalent. 

Some possible calls for this specification (with `X` and `Xi` having type_x):
 * `name(P, Q, R)`: `s` and `v` have their default values `v1` and `Enum1`
 * `name(P, [Q], R)`: equivalent to previous call
 * `name(P, [Q1, Q2], R, t=Enum2)`: `s` has its default value `v1`
 * `name(t=1, r=R, qs=[Q1, Q2], s=S1, p=P)` is equivalent to `name(P, [Q1, Q2], R, S1, 1)` 


== Notes ==
 * Parameters of type `bool` are specified by strings `true` or `false`
 * not case-sensitive
 * To get positions and keywords, use
{{{
--help [Name]
}}}

== Integers ==
Parameters of type `int` can be specified as "infinity". This means that the parameter will take the value `numeric_limits<int>::max()`, which is usually equal to 2^31 - 1. If an `int` parameter value ends with "K", "M" or "G", the value is multiplied by one thousand, one million or one billion, respectively. For example, "bound=2K" is equivalent to "bound=2000". 

== Strings ==
Parameters of type `string` can be specified in double quotes. Nested quotes can be escaped as `\"`, backslashes as `\\`, and newlines as `\n`.
E.g.,
{{{
filename="C:\\some.file"
}}}

== Lists ==
List arguments have to be enclosed in square brackets now.
E.g.,
{{{
--evaluator "hff=ff()" --evaluator "hcea=cea()" \
--search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
}}}

== Enumerations ==

Enumeration arguments should be specified by name, e.g.:
{{{
eager_greedy([h1,h2], cost_type=normal)
}}}

To get enumeration names (and more), run
{{{
--help [Name]   //e.g. with Name=eager_greedy
}}}

== Variables ==

Often an object should be used for several purposes, e.g. a [[Doc/Evaluator|Heuristic]] or a [[Doc/LandmarkFactory|LandmarkFactory]]. The most
prevalent use case is a heuristic that is used for both the heuristic 
estimates and for its preferred operators. In this case, one should define a variable for the object. We currently only support variables for
[[Doc/Evaluator|Heuristics]] and [[Doc/LandmarkFactory|LandmarkFactories]] but will extend the support for other feature types in the future.

Variables can be defined with {{{let(name, definition, expression)}}} 
 * `name`: a variable name that should denote the feature
 * `definition`: an expression defining the value of the variable
 * `expression`: an expression defining any other feature. Occurrences of `name` in this expression may refer to the feature defined by `definition`.


=== Variable Example ===

Suppose I want to run GBFS with the lm_count heuristic (the inadmissible version), and then run another GBFS search with an admissible lm_count heuristic,
using the h^m landmarks without discovering the landmarks twice. 

{{{
--search "let(lm, lm_hm(m=2), 
              iterated([lazy_greedy(lmcount(lm)),
                        lazy_greedy(lmcount(lm,admissible=true))]))" 
}}}


=== Old-style Predefinitions ===

We still support but deprecate the use of "predefinitions" before the {{{--search}}} option. They are internally converted to {{{let}}}-expressions.

The command lines
{{{
--evaluator name=definition --search expression
--landmarks name=definition --search expression
}}}
are both transformed to
{{{
--search let(name, definition, expression)
}}}


== Conditional options ==

In some cases, it is useful to specify different options depending on properties of the input file. For example, the LAMA 2011 configuration makes use of this, adding an additional cost-ignoring search run at the start for tasks with non-unit action costs.

=== Example ===

{{{
--if-unit-cost --evaluator "h1=ff()" --evaluator "h2=blind()" \
--if-non-unit-cost --evaluator "h1=cea()" --evaluator "h2=lmcut()" \
--always --search "eager_greedy([h1, h2])"
}}}

This conducts an eager greedy search with two heuristics. On unit-cost tasks, it uses the FF heuristic and the blind heuristic. On other tasks, it uses the context-enhanced additive heuristic and the LM-Cut heuristic.

=== Details ===

Options can be made conditional via ''selectors'' such as `--if-unit-cost`. All options following a selector are only used if the condition associated with the selector is true. (This really includes '''all''' options, including ones like `--plan-file` that do not affect the planning algorithm.) Each selector is in effect until it is overridden by a new selector. The following selectors are available:

 * `--if-unit-cost`: the following options are only used for unit-cost planning tasks (i.e., tasks where all actions have cost 1, including the case where no action costs are specified at all)
 * `--if-non-unit-cost`: opposite of `--if-unit-cost`
 * `--always`: the following options are always used