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erl_pp(3erl) | Erlang Module Definition | erl_pp(3erl) |
NAME¶
erl_pp - The Erlang pretty printer.DESCRIPTION¶
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.DATA 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 CurrentIndentation is negative, there are no line breaks and only a
space is used as a separator.
option() ={hook, hook_function()} | {encoding, latin1 | unicode | utf8}options() = hook_function() | [option()]
EXPORTS¶
attribute(Attribute) -> io_lib:chars()
attribute(Attribute, Options) -> io_lib:chars()
Types:
Attribute = erl_parse:abstract_form()
Options = options()
Same as form/1,2, but only for attribute Attribute.
expr(Expression) -> io_lib:chars()
expr(Expression, Options) -> io_lib:chars()
expr(Expression, Indent, Options) -> io_lib:chars()
expr(Expression, Indent, Precedence, Options) -> io_lib:chars()
Types:
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()
exprs(Expressions, Options) -> io_lib:chars()
exprs(Expressions, Indent, Options) -> io_lib:chars()
Types:
Expressions = [erl_parse:abstract_expr()]
Indent = integer()
Options = options()
Same as form/1,2, but only for the sequence of expressions in
Expressions.
form(Form) -> io_lib:chars()
form(Form, Options) -> io_lib:chars()
Types:
Form = erl_parse:abstract_form() |
erl_parse:form_info()
Options = options()
Pretty prints a Form, which is an abstract form of a type that is
returned by erl_parse:parse_form/1.
function(Function) -> io_lib:chars()
function(Function, Options) -> io_lib:chars()
Types:
Function = erl_parse:abstract_form()
Options = options()
Same as form/1,2, but only for function Function.
guard(Guard) -> io_lib:chars()
guard(Guard, Options) -> io_lib:chars()
Types:
Guard = [erl_parse:abstract_expr()]
Options = options()
Same as form/1,2, but only for the guard test Guard.
KNOWN LIMITATIONS¶
It is not possible to have hook functions for unknown forms at other places than expressions.SEE ALSO¶
erl_eval(3erl), erl_parse(3erl), io(3erl)stdlib 3.2 | Ericsson AB |