Constants used as whitespace chomping options.

CHOMP_NONE          # do not remove whitespace
CHOMP_ONE           # remove one line of whitespace
CHOMP_ALL           # remove all whitespace including newlines
CHOMP_SPACE         # collapse whitespace to single space
CHOMP_TAG           # remove the tag (e.g. [%# comment %])
PRE_CHOMP_FLAGS     # array ref of pre-chomp flags, e.g. '+', '-', '~', etc.
POST_CHOMP_FLAGS    # ditto for post-chomp flags

Constants used to control caching.

CACHE_ALL           # cache everything
CACHE_NONE          # cache nothing

Constants that define the default names for templates read from text strings and file handles, or constructed as wrappers around existing subroutines.

FROM_TEXT           # template text
FROM_CODE           # template code
FROM_HANDLE         # template read from file handle

Constants used as the scheme: prefix when constructing URIs for templates

TEXT_SCHEME         # text
FILE_SCHEME         # file
CODE_SCHEME         # code
NAME_SCHEME         # name
COLON               # :

Constants defining the names of the core services that Template::TT3::Engine::TT3 fetches from Template::TT3::Services to construct a template service pipeline.

INPUT_SERVICE       # input
OUTPUT_SERVICE      # output

Constants used by various Template::TT3::Element module to denote pre-define operator precedence levels

ARG_PRECEDENCE      # 200
CMD_PRECEDENCE      # 100

These constants define semantic aliases for the array offsets used by Template::TT3::Templates in its internal path lookup cache.

ID                  # 0
EXPIRES             # 1

Constants that represent the offsets of particular slots within array based objects. In this case they are the slots used by data types.

TODO: They need a good cleanup and the name should possible be changed to something more suitable.

    # variable data slots
    META                # 0
    CONTEXT             # 1
    NAME                # 2
    VALUE               # 3
    PARENT              # 4

    # variable metadata slots
    CONFIG              # 0
    VARS                # 1
    METHODS             # 2

Constants that represent the offsets of particular slots within Template::TT3::Element objects. The first 4 slots are common to all element types.

META                # 0
NEXT                # 1
TOKEN               # 2
POS                 # 3

The remaining slots have different meanings depending on the element type. Unary expressions (including those with blocks) refer to the next 2 slots as EXPR and BLOCK

EXPR                # 4
BLOCK               # 5

Binary expressions use LHS and RHS instead.

LHS                 # 4
RHS                 # 5

Expressions that have additional arguments put them in the next slot.

ARGS                # 6

Those that have an additional branch (e.g. the else hanging off an if block) store it in the BRANCH slot.

BRANCH              # 7

Any that have a fragment (e.g. end#for) store it in FRAGMENT.

FRAGMENT            # 8

The first slot in an element (META) contains a reference to a metadata structure which is also an array reference (an entry in the grammar symbol table - see the source code for Template::TT3::Grammar::TT3 for an example. The following constants define aliases for the slots in the metadata list.

CONFIG              # configuration parameters
ELEMS               # reference to elements factory
LPREC               # leftward precedence
RPREC               # rightward precedence

The final two constants are used by element evaluation methods.

SELF                # 0
CONTEXT             # 1

The element classes have many small methods that do very little. We try to avoid shifting items off the stack wherever possible (for the sake of speed) and instead reference arguments directly on the stack.

So instead of something like this:

sub some_method {
    my ($self, $context) = @_;
    $self->something_trivial($context);
}

You'll instead see:

sub some_method {
    $_[SELF]->something_trivial($_[CONTEXT]);
}

Which is slightly more meaningful than:

sub some_method {
    $_[0]->something_trivial($_[1]);
}

Imports all the constants defined by this module.