Pretty-printing.
This module implements a pretty-printing facility to format values within 'pretty-printing boxes'. The pretty-printer splits lines at specified break hints, and indents lines according to the box structure.
For a gentle introduction to the basics of pretty-printing using
Format, read
http://caml.inria.fr/resources/doc/guides/format.en.html.
You may consider this module as providing an extension to the
printf facility to provide automatic line splitting. The addition of
pretty-printing annotations to your regular printf format strings gives
you fancy indentation and line breaks.
Pretty-printing annotations are described below in the documentation of
the function Format.fprintf.
You may also use the explicit pretty-printing box management and printing
functions provided by this module. This style is more basic but more
verbose than the concise fprintf format strings.
For instance, the sequence
open_box 0; print_string "x ="; print_space ();
print_int 1; close_box (); print_newline ()
that prints x = 1 within a pretty-printing box, can be
abbreviated as printf "@[%s@ %i@]@." "x =" 1, or even shorter
printf "@[x =@ %i@]@." 1.
Rule of thumb for casual users of this library:
open_box 0);print_cut () that outputs a
simple break hint, or by print_space () that outputs a space
indicating a break hint;print_int and print_string);close_box () to close the box;print_newline ().The behavior of pretty-printing commands is unspecified
if there is no open pretty-printing box. Each box open via
one of the open_ functions below must be closed using close_box
for proper formatting. Otherwise, some of the material printed in the
boxes may not be output, or may be formatted incorrectly.
In case of interactive use, each phrase is executed in the initial state of the standard pretty-printer: after each phrase execution, the interactive system closes all open pretty-printing boxes, flushes all pending text, and resets the standard pretty-printer.
Warning: mixing calls to pretty-printing functions of this module with calls to Pervasives low level output functions is error prone.
The pretty-printing functions output material that is delayed in the
pretty-printer queue and stacks in order to compute proper line
splitting. In contrast, basic I/O output functions write directely in
their output device. As a consequence, the output of a basic I/O function
may appear before the output of a pretty-printing function that has been
called before. For instance,
Pervasives.print_string "<";
Format.print_string "PRETTY";
Pervasives.print_string ">";
Format.print_string "TEXT";
leads to output <>PRETTYTEXT.
The pretty-printing engine uses the concepts of pretty-printing box and break hint to drive the indentation and the line splitting behavior of the pretty-printer.
Each different pretty-printing box kind introduces a specific line splitting policy:
Note that line splitting policy is box specific: the policy of a box does not rule the policy of inner boxes. For instance, if a vertical box is nested in an horizontal box, all break hints within the vertical box will split the line.
val open_box : int -> unitopen_box d opens a new compacting pretty-printing box with offset d.
Within this box, the pretty-printer prints as much as possible material on every line.
A break hint splits the line if there is no more room on the line to print the remainder of the box.
Within this box, the pretty-printer emphasizes the box structure: a break hint also splits the line if the splitting ``moves to the left'' (i.e. the new line gets an indentation smaller than the one of the current line).
This box is the general purpose pretty-printing box.
If the pretty-printer splits the line in the box, offset d is added to
the current indentation.
val open_hbox : unit -> unitopen_hbox () opens a new 'horizontal' pretty-printing box.
This box prints material on a single line.
Break hints in a horizontal box never split the line. (Line splitting may still occur inside boxes nested deeper).
val open_vbox : int -> unitopen_vbox d opens a new 'vertical' pretty-printing box
with offset d.
This box prints material on as many lines as break hints in the box.
Every break hint in a vertical box splits the line.
If the pretty-printer splits the line in the box, d is added to the
current indentation.
val open_hvbox : int -> unitopen_hvbox d opens a new 'horizontal/vertical' pretty-printing box
with offset d.
This box behaves as an horizontal box if it fits on a single line, otherwise it behaves as a vertical box.
If the pretty-printer splits the line in the box, d is added to the
current indentation.
val open_hovbox : int -> unitopen_hovbox d opens a new 'horizontal-or-vertical' pretty-printing box
with offset d.
This box prints material as much as possible on every line.
A break hint splits the line if there is no more room on the line to print the remainder of the box.
If the pretty-printer splits the line in the box, d is added to the
current indentation.
val print_as : int -> string -> unitprint_as len s prints s in the current pretty-printing box.
The pretty-printer formats s as if it were of length len.
A 'break hint' tells the pretty-printer to output some space or split the line whichever way is more appropriate to the current pretty-printing box splitting rules.
Break hints are used to separate printing items and are mandatory to let the pretty-printer correctly split lines and indent items.
Simple break hints are:
Note: the notions of space and line splitting are abstract for the pretty-printing engine, since those notions can be completely redefined by the programmer. However, in the pretty-printer default setting, ``output a space'' simply means printing a space character (ASCII code 32) and ``split the line'' means printing a newline character (ASCII code 10).
val print_space : unit -> unitprint_space () emits a 'space' break hint:
the pretty-printer may split the line at this point,
otherwise it prints one space.
print_space is equivalent to print_break 1 0.
val print_cut : unit -> unitprint_cut () emits a 'cut' break hint:
the pretty-printer may split the line at this point,
otherwise it prints nothing.
print_cut is equivalent to print_break 0 0.
val print_break : int -> int -> unitprint_break nspaces offset emits a 'full' break hint:
the pretty-printer may split the line at this point,
otherwise it prints nspaces spaces.
If the pretty-printer splits the line, offset is added to
the current indentation.
val force_newline : unit -> unitForce a new line in the current pretty-printing box.
The pretty-printer must split the line at this point,
Not the normal way of pretty-printing, since imperative line splitting may interfere with current line counters and box size calculation. Using break hints within an enclosing vertical box is a better alternative.
val print_if_newline : unit -> unitExecute the next formatting command if the preceding line has just been split. Otherwise, ignore the next formatting command.
val print_flush : unit -> unitEnd of pretty-printing: resets the pretty-printer to initial state.
All open pretty-printing boxes are closed, all pending text is printed. In addition, the pretty-printer low level output device is flushed to ensure that all pending text is really displayed.
Note: never use print_flush in the normal course of a pretty-printing
routine, since the pretty-printer uses a complex buffering machinery to
properly indent the output; manually flushing those buffers at random
would conflict with the pretty-printer strategy and result to poor
rendering.
Only consider using print_flush when displaying all pending material is
mandatory (for instance in case of interactive use when you want the user
to read some text) and when resetting the pretty-printer state will not
disturb further pretty-printing.
Warning: If the output device of the pretty-printer is an output channel,
repeated calls to print_flush means repeated calls to Pervasives.flush
to flush the out channel; these explicit flush calls could foil the
buffering strategy of output channels and could dramatically impact
efficiency.
val print_newline : unit -> unitEnd of pretty-printing: resets the pretty-printer to initial state.
All open pretty-printing boxes are closed, all pending text is printed.
Equivalent to print_flush followed by a new line. See corresponding words of caution for print_flush.
Note: this is not the normal way to output a new line; the preferred method is using break hints within a vertical pretty-printing box.
val set_margin : int -> unitset_margin d sets the right margin to d (in characters):
the pretty-printer splits lines that overflow the right margin according to
the break hints given.
Nothing happens if d is smaller than 2.
If d is too large, the right margin is set to the maximum
admissible value (which is greater than 10 ^ 9).
val set_max_indent : int -> unitset_max_indent d sets the maximum indentation limit of lines to d (in
characters):
once this limit is reached, new pretty-printing boxes are rejected to the left,
if they do not fit on the current line.
Nothing happens if d is smaller than 2.
If d is too large, the limit is set to the maximum
admissible value (which is greater than 10 ^ 9).
The maximum formatting depth is the maximum allowed number of simultaneously open pretty-printing boxes before ellipsis.
val set_max_boxes : int -> unitset_max_boxes max sets the maximum number of pretty-printing boxes
simultaneously open.
Material inside boxes nested deeper is printed as an ellipsis (more
precisely as the text returned by get_ellipsis_text ()).
Nothing happens if max is smaller than 2.
val get_max_boxes : unit -> intReturns the maximum number of pretty-printing boxes allowed before ellipsis.
val over_max_boxes : unit -> boolTests if the maximum number of pretty-printing boxes allowed have already been open.
A tabulation box prints material on lines divided into cells of fixed length. A tabulation box provides a simple way to display vertical columns of left adjusted text.
This box features command set_tab to define cell boundaries, and command
print_tab to move from cell to cell and split the line when there is no
more cells to print on the line.
Note: printing within tabulation box is line directed, so arbitrary line splitting inside a tabulation box leads to poor rendering. Yet, controlled use of tabulation boxes allows simple printing of columns within Format.
val open_tbox : unit -> unitopen_tbox () opens a new tabulation box.
This box prints lines separated into cells of fixed width.
Inside a tabulation box, special tabulation markers defines points of interest on the line (for instance to delimit cell boundaries). Function Format.set_tab sets a tabulation marker at insertion point.
A tabulation box features specific tabulation breaks to move to next tabulation marker or split the line. Function Format.print_tbreak prints a tabulation break.
val print_tab : unit -> unitprint_tab () emits a 'next' tabulation break hint: if not already set on
a tabulation marker, the insertion point moves to the first tabulation
marker on the right, or the pretty-printer splits the line and insertion
point moves to the leftmost tabulation marker.
It is equivalent to print_tbreak 0 0.
val print_tbreak : int -> int -> unitprint_tbreak nspaces offset emits a 'full' tabulation break hint.
If not already set on a tabulation marker, the insertion point moves to the
first tabulation marker on the right and the pretty-printer prints
nspaces spaces.
If there is no next tabulation marker on the right, the pretty-printer splits the line at this point, then insertion point moves to the leftmost tabulation marker of the box.
If the pretty-printer splits the line, offset is added to
the current indentation.
val set_ellipsis_text : string -> unitSet the text of the ellipsis printed when too many pretty-printing boxes
are open (a single dot, ., by default).
Semantic tags (or simply tags) are user's defined delimiters to associate user's specific operations to printed entities.
Common usage of semantic tags is text decoration to get specific font or text size rendering for a display device, or marking delimitation of entities (e.g. HTML or TeX elements or terminal escape sequences). More sophisticated usage of semantic tags could handle dynamic modification of the pretty-printer behavior to properly print the material within some specific tags.
In order to properly delimit printed entities, a semantic tag must be opened before and closed after the entity. Semantic tags must be properly nested like parentheses.
Tag specific operations occur any time a tag is opened or closed, At each occurrence, two kinds of operations are performed tag-marking and tag-printing:
Roughly speaking, tag-marking is commonly used to get a better rendering of texts in the rendering device, while tag-printing allows fine tuning of printing routines to print the same entity differently according to the semantic tags (i.e. print additional material or even omit parts of the output).
More precisely: when a semantic tag is opened or closed then both and successive 'tag-printing' and 'tag-marking' operations occur:
print_open_tag (resp. print_close_tag) with the name of the tag as
argument: that tag-printing function can then print any regular material
to the formatter (so that this material is enqueued as usual in the
formatter queue for further line splitting computation).mark_open_tag (resp. mark_close_tag) with the name of the tag as
argument: that tag-marking function can then return the 'tag-opening
marker' (resp. `tag-closing marker') for direct output into the output
device of the formatter.Being written directly into the output device of the formatter, semantic tag marker strings are not considered as part of the printing material that drives line splitting (in other words, the length of the strings corresponding to tag markers is considered as zero for line splitting).
Thus, semantic tag handling is in some sense transparent to pretty-printing
and does not interfere with usual indentation. Hence, a single
pretty-printing routine can output both simple 'verbatim' material or
richer decorated output depending on the treatment of tags. By default,
tags are not active, hence the output is not decorated with tag
information. Once set_tags is set to true, the pretty-printer engine
honors tags and decorates the output accordingly.
Default tag-marking functions behave the HTML way: tags are enclosed in "<"
and ">"; hence, opening marker for tag t is "<t>" and closing marker is
"</t>".
Default tag-printing functions just do nothing.
Tag-marking and tag-printing functions are user definable and can be set by calling set_formatter_tag_functions.
Semantic tag operations may be set on or off with set_tags. Tag-marking operations may be set on or off with set_mark_tags. Tag-printing operations may be set on or off with set_print_tags.
val open_tag : tag -> unitopen_tag t opens the semantic tag named t.
The print_open_tag tag-printing function of the formatter is called with
t as argument; then the opening tag marker, as given by mark_open_tag t
is written into the output device of the formatter.
val close_tag : unit -> unitclose_tag () closes the most recently opened semantic tag t.
The closing tag marker, as given by mark_close_tag t, is written into the
output device of the formatter; then the print_close_tag tag-printing
function of the formatter is called with t as argument.
val set_tags : bool -> unitset_tags b turns on or off the treatment of semantic tags
(default is off).
val set_formatter_out_channel : Stdlib.Pervasives.out_channel -> unitRedirect the standard pretty-printer output to the given channel.
(All the output functions of the standard formatter are set to the
default output functions printing to the given channel.)
set_formatter_out_channel is equivalent to
pp_set_formatter_out_channel std_formatter.
val set_formatter_output_functions : (string -> int -> int -> unit) -> (unit -> unit) -> unitset_formatter_output_functions out flush redirects the
standard pretty-printer output functions to the functions out and
flush.
The out function performs all the pretty-printer string output.
It is called with a string s, a start position p, and a number of
characters n; it is supposed to output characters p to p + n - 1 of
s.
The flush function is called whenever the pretty-printer is flushed
(via conversion %!, or pretty-printing indications @? or @., or
using low level functions print_flush or print_newline).
val get_formatter_output_functions : unit -> (string -> int -> int -> unit) * (unit -> unit)Return the current output functions of the standard pretty-printer.
The Format module is versatile enough to let you completely redefine
the meaning of pretty-printing output: you may provide your own functions
to define how to handle indentation, line splitting, and even printing of
all the characters that have to be printed!
type formatter_out_functions = {out_string : string -> int -> int -> unit; |
out_flush : unit -> unit; |
out_newline : unit -> unit; |
out_spaces : int -> unit; |
out_indent : int -> unit; |
}The set of output functions specific to a formatter:
out_string function performs all the pretty-printer string output.
It is called with a string s, a start position p, and a number of
characters n; it is supposed to output characters p to p + n - 1 of
s.out_flush function flushes the pretty-printer output device.out_newline is called to open a new line when the pretty-printer splits
the line.out_spaces function outputs spaces when a break hint leads to spaces
instead of a line split. It is called with the number of spaces to output.out_indent function performs new line indentation when the
pretty-printer splits the line. It is called with the indentation value of
the new line.By default:
out_string and out_flush are output device specific;
(e.g. !Pervasives.output_string and !Pervasives.flush for a
!Pervasives.out_channel device, or Buffer.add_substring and
!Pervasives.ignore for a Buffer.t output device),out_newline is equivalent to out_string "\n" 0 1;out_spaces is equivalent to out_string (String.make n ' ') 0 n;out_indent is the same as field out_spaces.val set_formatter_out_functions : formatter_out_functions -> unitset_formatter_out_functions out_funs
Set all the pretty-printer output functions to those of argument
out_funs,
This way, you can change the meaning of indentation (which can be something else than just printing space characters) and the meaning of new lines opening (which can be connected to any other action needed by the application at hand).
val get_formatter_out_functions : unit -> formatter_out_functionsReturn the current output functions of the pretty-printer, including line splitting and indentation functions. Useful to record the current setting and restore it afterwards.
type formatter_tag_functions = {mark_open_tag : tag -> string; |
mark_close_tag : tag -> string; |
print_open_tag : tag -> unit; |
print_close_tag : tag -> unit; |
}The semantic tag handling functions specific to a formatter:
mark versions are the 'tag-marking' functions that associate a string
marker to a tag in order for the pretty-printing engine to write
those markers as 0 length tokens in the output device of the formatter.
print versions are the 'tag-printing' functions that can perform
regular printing when a tag is closed or opened.
val set_formatter_tag_functions : formatter_tag_functions -> unitset_formatter_tag_functions tag_funs changes the meaning of
opening and closing semantic tag operations to use the functions in
tag_funs.
When opening a semantic tag name t, the string t is passed to the
opening tag-marking function (the mark_open_tag field of the
record tag_funs), that must return the opening tag marker for
that name. When the next call to close_tag () happens, the semantic tag
name t is sent back to the closing tag-marking function (the
mark_close_tag field of record tag_funs), that must return a
closing tag marker for that name.
The print_ field of the record contains the tag-printing functions that
are called at tag opening and tag closing time, to output regular material
in the pretty-printer queue.
val get_formatter_tag_functions : unit -> formatter_tag_functionsReturn the current semantic tag operation functions of the standard pretty-printer.
type formatterAbstract data corresponding to a pretty-printer (also called a formatter) and all its machinery.
Defining new formatters permits unrelated output of material in parallel on several output devices. All the parameters of a formatter are local to the formatter: right margin, maximum indentation limit, maximum number of pretty-printing boxes simultaneously open, ellipsis, and so on, are specific to each formatter and may be fixed independently.
For instance, given a !Buffer.t buffer b, formatter_of_buffer b
returns a new formatter using buffer b as its output device.
Similarly, given a !Pervasives.out_channel output channel oc,
formatter_of_out_channel oc returns a new formatter using
channel oc as its output device.
Alternatively, given out_funs, a complete set of output functions for a
formatter, then formatter_of_out_function out_funs computes a new
formatter using those functions for output.
val formatter_of_out_channel : Stdlib.out_channel -> formatterformatter_of_out_channel oc returns a new formatter writing
to the corresponding channel oc.
val std_formatter : formatterThe standard formatter to write to standard output.
It is defined as formatter_of_out_channel stdout.
val err_formatter : formatterA formatter to to write to standard error.
It is defined as formatter_of_out_channel stderr.
val formatter_of_buffer : Stdlib.Buffer.t -> formatterformatter_of_buffer b returns a new formatter writing to
buffer b. At the end of pretty-printing, the formatter must be flushed
using pp_print_flush or pp_print_newline, to print all the pending
material into the buffer.
val str_formatter : formatterA formatter to output to the stdbuf string buffer.
str_formatter is defined as formatter_of_buffer stdbuf.
val flush_str_formatter : unit -> stringReturns the material printed with str_formatter, flushes
the formatter and resets the corresponding buffer.
val make_formatter : (string -> int -> int -> unit) -> (unit -> unit) -> formattermake_formatter out flush returns a new formatter that outputs with
function out, and flushes with function flush.
For instance, a formatter to the !Pervasives.out_channeloc is returned
by make_formatter (!Pervasives.output oc) (fun () -> !Pervasives.flush
oc).
val formatter_of_out_functions : formatter_out_functions -> formatterformatter_of_out_functions out_funs returns a new formatter that writes
with the set of output functions out_funs.
See definition of type formatter_out_functions for the meaning of argument
out_funs.
Symbolic pretty-printing is pretty-printing with no low level output.
When using a symbolic formatter, all regular pretty-printing activities occur but output material is symbolic and stored in a buffer of output items. At the end of pretty-printing, flushing the output buffer allows post-processing of symbolic output before low level output operations.
type symbolic_output_item = val make_symbolic_output_buffer : unit -> symbolic_output_buffermake_symbolic_output_buffer () returns a fresh buffer for
symbolic output.
val clear_symbolic_output_buffer : symbolic_output_buffer -> unitclear_symbolic_output_buffer sob resets buffer sob.
val get_symbolic_output_buffer : symbolic_output_buffer -> symbolic_output_item listget_symbolic_output_buffer sob returns the contents of buffer sob.
val flush_symbolic_output_buffer : symbolic_output_buffer -> symbolic_output_item listflush_symbolic_output_buffer sob returns the contents of buffer
sob and resets buffer sob.
flush_symbolic_output_buffer sob is equivalent to
let items = get_symbolic_output_buffer sob in
clear_symbolic_output_buffer sob; items
val add_symbolic_output_item : symbolic_output_buffer -> symbolic_output_item -> unitadd_symbolic_output_item sob itm adds item itm to buffer sob.
val formatter_of_symbolic_output_buffer : symbolic_output_buffer -> formatterformatter_of_symbolic_output_buffer sob returns a symbolic formatter
that outputs to symbolic_output_buffersob.
val pp_open_hbox : formatter -> unit -> unitval pp_open_vbox : formatter -> int -> unitval pp_open_hvbox : formatter -> int -> unitval pp_open_hovbox : formatter -> int -> unitval pp_open_box : formatter -> int -> unitval pp_close_box : formatter -> unit -> unitval pp_open_tag : formatter -> string -> unitval pp_close_tag : formatter -> unit -> unitval pp_print_string : formatter -> string -> unitval pp_print_as : formatter -> int -> string -> unitval pp_print_int : formatter -> int -> unitval pp_print_float : formatter -> float -> unitval pp_print_char : formatter -> char -> unitval pp_print_bool : formatter -> bool -> unitval pp_print_break : formatter -> int -> int -> unitval pp_print_cut : formatter -> unit -> unitval pp_print_space : formatter -> unit -> unitval pp_force_newline : formatter -> unit -> unitval pp_print_flush : formatter -> unit -> unitval pp_print_newline : formatter -> unit -> unitval pp_print_if_newline : formatter -> unit -> unitval pp_set_tags : formatter -> bool -> unitval pp_set_print_tags : formatter -> bool -> unitval pp_set_mark_tags : formatter -> bool -> unitval pp_get_print_tags : formatter -> unit -> boolval pp_get_mark_tags : formatter -> unit -> boolval pp_set_margin : formatter -> int -> unitval pp_get_margin : formatter -> unit -> intval pp_set_max_indent : formatter -> int -> unitval pp_get_max_indent : formatter -> unit -> intval pp_set_max_boxes : formatter -> int -> unitval pp_get_max_boxes : formatter -> unit -> intval pp_over_max_boxes : formatter -> unit -> boolval pp_set_ellipsis_text : formatter -> string -> unitval pp_get_ellipsis_text : formatter -> unit -> stringval pp_set_formatter_out_channel : formatter -> Stdlib.Pervasives.out_channel -> unitval pp_set_formatter_output_functions : formatter -> (string -> int -> int -> unit) -> (unit -> unit) -> unitval pp_get_formatter_output_functions : formatter -> unit -> (string -> int -> int -> unit) * (unit -> unit)val pp_set_formatter_tag_functions : formatter -> formatter_tag_functions -> unitval pp_get_formatter_tag_functions : formatter -> unit -> formatter_tag_functionsval pp_get_formatter_out_functions : formatter -> unit -> formatter_out_functionsThese functions are the basic ones: usual functions
operating on the standard formatter are defined via partial
evaluation of these primitives. For instance,
print_string is equal to pp_print_string std_formatter.
val pp_print_list : ?pp_sep:(formatter -> unit -> unit) -> (formatter -> 'a -> unit) -> formatter -> 'a list -> unitpp_print_list ?pp_sep pp_v ppf l prints items of list l,
using pp_v to print each item, and calling pp_sep
between items (pp_sep defaults to pp_print_cut).
Does nothing on empty lists.
val pp_print_text : formatter -> string -> unitpp_print_text ppf s prints s with spaces and newlines respectively
printed using pp_print_space and pp_force_newline.
Module Format provides a complete set of printf like functions for
pretty-printing using format string specifications.
Specific annotations may be added in the format strings to give pretty-printing commands to the pretty-printing engine.
Those annotations are introduced in the format strings using the @
character. For instance, @ means a space break, @, means a cut,
@[ opens a new box, and @] closes the last open box.
val fprintf : formatter -> ('a, formatter, unit) Stdlib.format -> 'afprintf ff fmt arg1 ... argN formats the arguments arg1 to argN
according to the format string fmt, and outputs the resulting string on
the formatter ff.
The format string fmt is a character string which contains three types of
objects: plain characters and conversion specifications as specified in
the Printf module, and pretty-printing indications specific to the
Format module.
The pretty-printing indication characters are introduced by
a @ character, and their meanings are:
@[: open a pretty-printing box. The type and offset of the
box may be optionally specified with the following syntax:
the < character, followed by an optional box type indication,
then an optional integer offset, and the closing > character.
Pretty-printing box type is one of h, v, hv, b, or hov.
'h' stands for an 'horizontal' pretty-printing box,
'v' stands for a 'vertical' pretty-printing box,
'hv' stands for an 'horizontal/vertical' pretty-printing box,
'b' stands for an 'horizontal-or-vertical' pretty-printing box
demonstrating indentation,
'hov' stands a simple 'horizontal-or-vertical' pretty-printing box.
For instance, @[<hov 2> opens an 'horizontal-or-vertical'
pretty-printing box with indentation 2 as obtained with open_hovbox 2.
For more details about pretty-printing boxes, see the various box opening
functions open_*box.@]: close the most recently opened pretty-printing box.@,: output a 'cut' break hint, as with print_cut ().@ : output a 'space' break hint, as with print_space ().@;: output a 'full' break hint as with print_break. The
nspaces and offset parameters of the break hint may be
optionally specified with the following syntax:
the < character, followed by an integer nspaces value,
then an integer offset, and a closing > character.
If no parameters are provided, the good break defaults to a
'space' break hint.@.: flush the pretty-printer and split the line, as with
print_newline ().@<n>: print the following item as if it were of length n.
Hence, printf "@<0>%s" arg prints arg as a zero length string.
If @<n> is not followed by a conversion specification,
then the following character of the format is printed as if
it were of length n.@{: open a semantic tag. The name of the tag may be optionally
specified with the following syntax:
the < character, followed by an optional string
specification, and the closing > character. The string
specification is any character string that does not contain the
closing character '>'. If omitted, the tag name defaults to the
empty string.
For more details about semantic tags, see the functions {!open_tag} and
{!close_tag}.@}: close the most recently opened semantic tag.@?: flush the pretty-printer as with print_flush ().
This is equivalent to the conversion %!.@\n: force a newline, as with force_newline (), not the normal way
of pretty-printing, you should prefer using break hints inside a vertical
pretty-printing box.Note: To prevent the interpretation of a @ character as a
pretty-printing indication, escape it with a % character.
Old quotation mode @@ is deprecated since it is not compatible with
formatted input interpretation of character '@'.
Example: printf "@[%s@ %d@]@." "x =" 1 is equivalent to
open_box (); print_string "x ="; print_space ();
print_int 1; close_box (); print_newline ().
It prints x = 1 within a pretty-printing 'horizontal-or-vertical' box.
val printf : ('a, formatter, unit) Stdlib.format -> 'aSame as fprintf above, but output on std_formatter.
val eprintf : ('a, formatter, unit) Stdlib.format -> 'aSame as fprintf above, but output on err_formatter.
val sprintf : ('a, unit, string) Stdlib.format -> 'aSame as printf above, but instead of printing on a formatter,
returns a string containing the result of formatting the arguments.
Note that the pretty-printer queue is flushed at the end of each
call to sprintf.
In case of multiple and related calls to sprintf to output
material on a single string, you should consider using fprintf
with the predefined formatter str_formatter and call
flush_str_formatter () to get the final result.
Alternatively, you can use Format.fprintf with a formatter writing to a
buffer of your own: flushing the formatter and the buffer at the end of
pretty-printing returns the desired string.
val asprintf : ('a, formatter, unit, string) Stdlib.format4 -> 'aSame as printf above, but instead of printing on a formatter,
returns a string containing the result of formatting the arguments.
The type of asprintf is general enough to interact nicely with %a
conversions.
val ifprintf : formatter -> ('a, formatter, unit) Stdlib.format -> 'aSame as fprintf above, but does not print anything.
Useful to ignore some material when conditionally printing.
Formatted Pretty-Printing with continuations.
val kfprintf : (formatter -> 'a) -> formatter -> ('b, formatter, unit, 'a) Stdlib.format4 -> 'bSame as fprintf above, but instead of returning immediately,
passes the formatter to its first argument at the end of printing.
val ikfprintf : (formatter -> 'a) -> formatter -> ('b, formatter, unit, 'a) Stdlib.format4 -> 'bSame as kfprintf above, but does not print anything.
Useful to ignore some material when conditionally printing.
val ksprintf : (string -> 'a) -> ('b, unit, string, 'a) Stdlib.format4 -> 'bSame as sprintf above, but instead of returning the string,
passes it to the first argument.
val kasprintf : (string -> 'a) -> ('b, formatter, unit, 'a) Stdlib.format4 -> 'bSame as asprintf above, but instead of returning the string,
passes it to the first argument.
val bprintf : Stdlib.Buffer.t -> ('a, formatter, unit) Stdlib.format -> 'aDeprecated This function is error prone. Do not use it. This function is neither compositional nor incremental, since it flushes the pretty-printer queue at each call.
If you need to print to some buffer b, you must first define a
formatter writing to b, using let to_b = formatter_of_buffer b; then
use regular calls to Format.fprintf with formatter to_b.
val kprintf : (string -> 'a) -> ('b, unit, string, 'a) Stdlib.format4 -> 'bksprintf.val set_all_formatter_output_functions : out:(string -> int -> int -> unit) -> flush:(unit -> unit) -> newline:(unit -> unit) -> spaces:(int -> unit) -> unitset_formatter_out_functions.val get_all_formatter_output_functions : unit -> (string -> int -> int -> unit) * (unit -> unit) * (unit -> unit) * (int -> unit)get_formatter_out_functions.val pp_set_all_formatter_output_functions : formatter -> out:(string -> int -> int -> unit) -> flush:(unit -> unit) -> newline:(unit -> unit) -> spaces:(int -> unit) -> unitpp_set_formatter_out_functions.val pp_get_all_formatter_output_functions : formatter -> unit -> (string -> int -> int -> unit) * (unit -> unit) * (unit -> unit) * (int -> unit)pp_get_formatter_out_functions.