The Erlang pretty printer.
The functions in this module are used to generate aesthetically attractive representations of abstract forms, which are suitable for printing. All functions return (possibly deep) lists of characters and generate an error if the form is wrong.
All functions can have an optional argument, which specifies a hook that is called if an attempt is made to print an unknown form.
Types
hook_function() =
none |
fun((Expr :: erl_parse:abstract_expr(),
CurrentIndentation :: integer(),
CurrentPrecedence :: integer() >= 0,
Options :: options()) ->
io_lib:chars())
Optional argument HookFunction
,
shown in the functions described in this module, defines a function
that is called when an unknown form occurs where there
is to be a valid expression. If HookFunction
is equal to
none
, there is no hook function.
The called hook function is to return a (possibly deep) list of
characters. Function expr/4
is useful in a hook.
If
is negative, there are no
line breaks and only a space is used as a separator.
option() =
{hook, hook_function()} |
{encoding, latin1 | unicode | utf8} |
{quote_singleton_atom_types, boolean()}
The option quote_singleton_atom_types
is used to add quotes to all singleton atom types.
options() = hook_function() | [option()]
Functions
attribute(Attribute) -> io_lib:chars()
Attribute = erl_parse:abstract_form()
attribute(Attribute, Options) -> io_lib:chars()
Attribute = erl_parse:abstract_form()
Options = options()
Same as form/1,2
,
but only for attribute
.
expr(Expression) -> io_lib:chars()
Expression = erl_parse:abstract_expr()
expr(Expression, Options) -> io_lib:chars()
Expression = erl_parse:abstract_expr()
Options = options()
expr(Expression, Indent, Options) -> io_lib:chars()
Expression = erl_parse:abstract_expr()
Indent = integer()
Options = options()
expr(Expression, Indent, Precedence, Options) -> io_lib:chars()
Expression = erl_parse:abstract_expr()
Indent = integer()
Precedence = integer() >= 0
Options = options()
Prints one expression. It is useful for implementing hooks (see section Known Limitations).
exprs(Expressions) -> io_lib:chars()
Expressions = [erl_parse:abstract_expr()]
exprs(Expressions, Options) -> io_lib:chars()
Expressions = [erl_parse:abstract_expr()]
Options = options()
exprs(Expressions, Indent, Options) -> io_lib:chars()
Expressions = [erl_parse:abstract_expr()]
Indent = integer()
Options = options()
Same as form/1,2
,
but only for the sequence of
expressions in
.
form(Form) -> io_lib:chars()
form(Form, Options) -> io_lib:chars()
Form = erl_parse:abstract_form() | erl_parse:form_info()
Options = options()
Pretty prints a
, which is an abstract form of a type that is
returned by
erl_parse:parse_form/1
.
function(Function) -> io_lib:chars()
Function = erl_parse:abstract_form()
function(Function, Options) -> io_lib:chars()
Function = erl_parse:abstract_form()
Options = options()
Same as form/1,2
,
but only for function
.
guard(Guard) -> io_lib:chars()
Guard = [erl_parse:abstract_expr()]
guard(Guard, Options) -> io_lib:chars()
Guard = [erl_parse:abstract_expr()]
Options = options()
Same as form/1,2
,
but only for the guard test
.
Known Limitations
It is not possible to have hook functions for unknown forms at other places than expressions.