Improved docstring
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README.md
160
README.md
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@ -1,160 +0,0 @@
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# Pretty #
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`pretty` is an advanced pretty printer for [Lua](lua.org). It's primarily a
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debugging tool, aiming for human readability, by detecting pattern in the input
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data, and creating an output string utilizing and highlighting those patterns.
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## Code Example
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Setup is simple, use `pretty = require 'pretty'`, and you're good to go.
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```lua
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> print(pretty( { 1, 2, 3 } ))
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{ 1, 2, 3 }
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> print(pretty( { hello = 'world', num = 42 } ))
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{
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num = 42
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hello = 'world'
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}
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> print(pretty( { abs = math.abs, max = math.max, some = function() end } ))
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{
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abs = builtin function (x) ... end
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max = builtin function (x, ...) ... end
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some = function () ... end
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}
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> print(pretty( math.abs ))
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builtin function (x)
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-- math.abs
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-- Returns the absolute value of x
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...
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end
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```
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## Motivation
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This project is the outcome of my frustration with existing pretty printers, and
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a desire to expand upon the pretty printer I developed for
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[Xenoterm](https://gitfub.space/takunomi/Xenoterm). The original Xenoterm pretty
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printer was much simpler than `pretty` - and the current is even simpler - but
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the enhancements I make, when compared to other pretty printers, inspired me to
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create `pretty`.
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`pretty` sorts it's priorities like so:
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1. Human readability.
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2. Lua-compatible output.
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3. Customization.
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I'd rather have good defaults than provide a ton of customization options. If an
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structure avoids easy representation in Lua, I'd rather extend the syntax, than
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lose the info.
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Another aspect where `pretty` shines is in exploratory programming, when
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attempting to avoid reliance on outside documentation. The amount of information
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`pretty` exposes varies by the data you are inspecting. If you're inspecting
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a list of functions, their function signatures are visible, but if you're
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inspecting a single function, documentation and source location may appear if
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available.
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## Features
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- Written in good-old pureblood Lua, with support for PUC Lua 5.0+ and
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LuaJIT 2.0+.
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- Redefining what it means to be "human readable":
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* Is multi-line centric, to aid readablitiy.
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* Indention and alignment of keys-value pairs.
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* Keys-value pairs are [properly](http://www.davekoelle.com/alphanum.html)
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sorted by key type and thereafter alphabetically.
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* The format and structure of output changes depending upon the input.
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Maps appear differently to deeply nested tables to long sequences
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with short strings to short lists.
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* Uses the standard `debug` library to gain information about functions
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and other advanced structures.
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## Installation
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`pretty` is loadable directly with `require`. Either clone or download this
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repository. Where you place it, depends upon what you want to do:
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1. **You want `pretty` in a specific project**: Place the `pretty` folder
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somewhere in your project, and `require` it from one of your project files.
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2. **You want `pretty` on your system**: Place the `pretty` folder such that
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it's visible from your Lua-path. On my system this might be
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`/usr/local/share/lua/5.1/`. Now you can `require` it from anywhere.
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## API Documentation
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`pretty` exposes a single function, the `pretty` function itself. It's function
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signature is `pretty(value, options)`. `value` can be any Lua value. `options`
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must be a table.
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### List of options
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`pretty` is sure to complain if you give it an unknown option, or if you give an
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option a bad value.
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- `indent: string`: The string to indent with. Four spaces by default.
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## TODO
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Tasks to be done before `pretty` can be called version 1.0.0, in order of
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priority:
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- Add a dedicated unicode submodule, to handle some minor alignment and
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character escaping issues. `pretty` should escape all malformed unicode
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sequences.
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- Align numbers towards right for tabular views.
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- Add support for `setmetatable`, and exploring values in metatables.
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- Provide nice formatting for `cdata` datatype in LuaJIT.
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- Find a better name than `pretty`.
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- Enhance internal structure some amount. See `TODO` markers in files.
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It would be nice to have the following, but these are secondary:
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- Add option for colored output. Primarily syntax highlighting, but also
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[BlueJ-style](www.bluej.org/about.html) scope highlighting, with some faint
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background colors.
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- Expand on the comment output in output, for `__tostring` methods, and global
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namespaces like `io` or `math`.
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- Fit output within a predefined width limit. Default to 80.
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- Look into tool for understanding complex structures with recursive
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definitions. Whatever modes are thought up, they should be automatic modes,
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not an options. Should at least include modes for self-referential tables
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and Directed-Acyclic-Graphs.
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## Alternative pretty printers
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`pretty` is large, slow, and requires the debug library to work. It's not
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designed for serialization purposes, nor is it concerned with offering the same
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level of customization as other libraries do.
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If you want a sleek, fast, customizable or embeddable library, there are
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thankfully other options.
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- [inspect.lua](github.com/kikito/inspect.lua): One of the classic debugging
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pretty printers.
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- [pprint.lua](github.com/jagt/pprint.lua): Reimplementation of `inspect.lua`
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- [serpent](github.com/pkulchenko/serpent): Advanced and fast pretty printer.
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- [pluto](lua-users.org/wiki/PlutoLibrary): Can serialize arbitrary parts of
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Lua, including functions, upvalues, and proper lexical scoping. Not written
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in native Lua.
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- [binser](github.com/bakpakin/binser): Library for special purpose
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serialization.
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Even more are available at [the lua-users wiki](lua-users.org/wiki/TableSerialization).
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## Contact
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The author is available at `jonjmaa (at) gmail.com`. Be sure to send an email if
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you have ideas for improvements, or find an issue.
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## License
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The license is the BeerWare license - Please see the
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[LICENSE.txt](https://gitfub.space/Jmaa/pretty/blob/master/LICENSE.txt) file for
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details.
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248
pretty.lua
248
pretty.lua
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@ -1,57 +1,197 @@
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-- pretty.pretty
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-- Main module of the `pretty` library.
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-- TODO: Maybe move table formatting into its own file?
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--[=[ Thoughts on displaying tables in an intuitive way.
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Lua's table data-structure is likely to be the most concise data structure ever
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invented. (If not, please send me a link!) Lists, maps, objects, classes,
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proxies, etc. This obviously brings about it some difficulty when attempting to
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represent these tables. What do we want to highlight, and what do we choose to
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avoid?
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One notable issue is whether to show every key that a table answers (to lift
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some Smalltalk terms) to, or to just display those it contains. That is, do we
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think about `__index` in the table's metatable and what it returns, or do we
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ignore `__index`? For cases where `__index` is a function, we cannot say
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anything about the keys that the table answers to. If `__index` is a table, we
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have a better idea, but it would be cluttered to display both types of keys side
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by side.
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1. Native representation: Lua's native representation includes the type and
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address of the table. It allows for distinguishing between unique tables,
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but won't tell us anything about the contents.
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2. Omission: By representing tables as the pseudo-parsable `{...}`, it's
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clear we are talking about a table. We disregard the ability to
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distinguish between tables.
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2A. If the table is empty, we could represent it as `{}`. But what if the table
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has a metatable with `__index` defined? We could continue to represent it as
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`{}`, but `{...}` would be more "honest".
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3. Single-line: TODO
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4. Multi-line: TODO
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5. Columns: For some highly-regular structures, like lists of short strings,
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giving each string it's own line would be too long, but formatting them as a
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single-line list would be too cluttered. Thus we can take inspiration from
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the classic `ls` unix tool, and place the output into columns, to help guide
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the eyes.
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6. Tabular: Other structures are formatted like actual tables of data, e.g. a
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sequence of tuples, like one would see in an SQL database. For these
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structures it's an obvious choice to align them based on the keys.
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7. Pseudo-Tabular: Some structures are almost tabular, e.g. they are sequences
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of tuples, but some of the tuples differ in their structure. For these
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structures it's still useful to tabulate the keys that all tuples share. To
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do this we should sort the key order descending by the number of tuples with
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the key.
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But what do we do about the the outlier keys? We can either justify the
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entire table, and give specific spots for the outlier keys, thereby
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significantly increasing the size of the table, or we can leave the table
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unjustified, abandoning it's eye-guiding attributes.
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8. Special cases: (Array-tree, Table-Tree, Linked-List, Predictive Sequences) TODO
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--]=]
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--- Pretty
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--
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-- `pretty` is an advanced pretty printer for [Lua](lua.org). It's primarily a
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-- debugging tool, aiming for human readability, by detecting pattern in the input
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-- data, and creating an output string utilizing and highlighting those patterns.
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--
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-- ## Code Example
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--
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-- Setup is simple, use `pretty = require 'pretty'`, and you're good to go.
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--
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-- ```lua
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-- > print(pretty( { 1, 2, 3 } ))
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-- { 1, 2, 3 }
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--
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-- > print(pretty( { hello = 'world', num = 42 } ))
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-- {
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-- num = 42
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-- hello = 'world'
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-- }
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--
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-- > print(pretty( { abs = math.abs, max = math.max, some = function() end } ))
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-- {
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-- abs = builtin function (x) ... end
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-- max = builtin function (x, ...) ... end
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-- some = function () ... end
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-- }
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--
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-- > print(pretty( math.abs ))
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-- builtin function (x)
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-- -- math.abs
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-- -- Returns the absolute value of x
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--
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-- ...
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-- end
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-- ```
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--
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-- ## Motivation
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--
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-- This project is the outcome of my frustration with existing pretty printers, and
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-- a desire to expand upon the pretty printer I developed for
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-- [Xenoterm](https://gitfub.space/takunomi/Xenoterm). The original Xenoterm pretty
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-- printer was much simpler than `pretty` - and the current is even simpler - but
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-- the enhancements I make, when compared to other pretty printers, inspired me to
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-- create `pretty`.
|
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--
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-- `pretty` sorts it's priorities like so:
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--
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-- 1. Human readability.
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-- 2. Lua-compatible output.
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-- 3. Customization.
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--
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-- I'd rather have good defaults than provide a ton of customization options. If an
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-- structure avoids easy representation in Lua, I'd rather extend the syntax, than
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-- lose the info.
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--
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-- Another aspect where `pretty` shines is in exploratory programming, when
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-- attempting to avoid reliance on outside documentation. The amount of information
|
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-- `pretty` exposes varies by the data you are inspecting. If you're inspecting
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-- a list of functions, their function signatures are visible, but if you're
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-- inspecting a single function, documentation and source location may appear if
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-- available.
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--
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-- ## Features
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--
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-- - Written in good-old pureblood Lua, with support for PUC Lua 5.0+ and
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-- LuaJIT 2.0+.
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-- - Redefining what it means to be "human readable":
|
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-- * Is multi-line centric, to aid readablitiy.
|
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-- * Indention and alignment of keys-value pairs.
|
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-- * Keys-value pairs are [properly](http://www.davekoelle.com/alphanum.html)
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-- sorted by key type and thereafter alphabetically.
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-- * The format and structure of output changes depending upon the input.
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-- Maps appear differently to deeply nested tables to long sequences
|
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-- with short strings to short lists.
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-- * Uses the standard `debug` library to gain information about functions
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-- and other advanced structures.
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--
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-- ## Installation
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--
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-- `pretty` is loadable directly with `require`. Either clone or download this
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-- repository. Where you place it, depends upon what you want to do:
|
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--
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-- 1. **You want `pretty` in a specific project**: Place the `pretty` folder
|
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-- somewhere in your project, and `require` it from one of your project files.
|
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-- 2. **You want `pretty` on your system**: Place the `pretty` folder such that
|
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-- it's visible from your Lua-path. On my system this might be
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-- `/usr/local/share/lua/5.1/`. Now you can `require` it from anywhere.
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--
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-- ## API Documentation
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--
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-- `pretty` exposes a single function, the `pretty` function itself. It's function
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-- signature is `pretty(value, options)`. `value` can be any Lua value. `options`
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-- must be a table.
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--
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-- ### List of options
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--
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-- `pretty` is sure to complain if you give it an unknown option, or if you give an
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-- option a bad value.
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--
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-- - `indent: string`: The string to indent with. Four spaces by default.
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--
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-- ## TODO
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--
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-- Tasks to be done before `pretty` can be called version 1.0.0, in order of
|
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-- priority:
|
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--
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-- - Add a dedicated unicode submodule, to handle some minor alignment and
|
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-- character escaping issues. `pretty` should escape all malformed unicode
|
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-- sequences.
|
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-- - Align numbers towards right for tabular views.
|
||||
-- - Add support for `setmetatable`, and exploring values in metatables.
|
||||
-- - Provide nice formatting for `cdata` datatype in LuaJIT.
|
||||
-- - Find a better name than `pretty`.
|
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-- - Enhance internal structure some amount. See `TODO` markers in files.
|
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--
|
||||
-- It would be nice to have the following, but these are secondary:
|
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--
|
||||
-- - Add option for colored output. Primarily syntax highlighting, but also
|
||||
-- [BlueJ-style](www.bluej.org/about.html) scope highlighting, with some faint
|
||||
-- background colors.
|
||||
-- - Expand on the comment output in output, for `__tostring` methods, and global
|
||||
-- namespaces like `io` or `math`.
|
||||
-- - Fit output within a predefined width limit. Default to 80.
|
||||
-- - Look into tool for understanding complex structures with recursive
|
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-- definitions. Whatever modes are thought up, they should be automatic modes,
|
||||
-- not an options. Should at least include modes for self-referential tables
|
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-- and Directed-Acyclic-Graphs.
|
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--
|
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-- ## Alternative pretty printers
|
||||
--
|
||||
-- `pretty` is large, slow, and requires the debug library to work. It's not
|
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-- designed for serialization purposes, nor is it concerned with offering the same
|
||||
-- level of customization as other libraries do.
|
||||
--
|
||||
-- If you want a sleek, fast, customizable or embeddable library, there are
|
||||
-- thankfully other options.
|
||||
--
|
||||
-- - [inspect.lua](github.com/kikito/inspect.lua): One of the classic debugging
|
||||
-- pretty printers.
|
||||
-- - [pprint.lua](github.com/jagt/pprint.lua): Reimplementation of `inspect.lua`
|
||||
-- - [serpent](github.com/pkulchenko/serpent): Advanced and fast pretty printer.
|
||||
-- - [pluto](lua-users.org/wiki/PlutoLibrary): Can serialize arbitrary parts of
|
||||
-- Lua, including functions, upvalues, and proper lexical scoping. Not written
|
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-- in native Lua.
|
||||
-- - [binser](github.com/bakpakin/binser): Library for special purpose
|
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-- serialization.
|
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--
|
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-- Even more are available at [the lua-users wiki](lua-users.org/wiki/TableSerialization).
|
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--
|
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-- ## Thoughts on displaying tables in an intuitive way.
|
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--
|
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-- Lua's table data-structure is likely to be the most concise data structure ever
|
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-- invented. (If not, please send me a link!) Lists, maps, objects, classes,
|
||||
-- proxies, etc. This obviously brings about it some difficulty when attempting to
|
||||
-- represent these tables. What do we want to highlight, and what do we choose to
|
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-- avoid?
|
||||
--
|
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-- One notable issue is whether to show every key that a table answers (to lift
|
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-- some Smalltalk terms) to, or to just display those it contains. That is, do we
|
||||
-- think about `__index` in the table's metatable and what it returns, or do we
|
||||
-- ignore `__index`? For cases where `__index` is a function, we cannot say
|
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-- anything about the keys that the table answers to. If `__index` is a table, we
|
||||
-- have a better idea, but it would be cluttered to display both types of keys side
|
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-- by side.
|
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--
|
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-- 1. Native representation: Lua's native representation includes the type and
|
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-- address of the table. It allows for distinguishing between unique tables,
|
||||
-- but won't tell us anything about the contents.
|
||||
-- 2. Omission: By representing tables as the pseudo-parsable `{...}`, it's
|
||||
-- clear we are talking about a table. We disregard the ability to
|
||||
-- distinguish between tables.
|
||||
-- 2A. If the table is empty, we could represent it as `{}`. But what if the table
|
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-- has a metatable with `__index` defined? We could continue to represent it as
|
||||
-- `{}`, but `{...}` would be more "honest".
|
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-- 3. Single-line: TODO
|
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-- 4. Multi-line: TODO
|
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-- 5. Columns: For some highly-regular structures, like lists of short strings,
|
||||
-- giving each string it's own line would be too long, but formatting them as a
|
||||
-- single-line list would be too cluttered. Thus we can take inspiration from
|
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-- the classic `ls` unix tool, and place the output into columns, to help guide
|
||||
-- the eyes.
|
||||
-- 6. Tabular: Other structures are formatted like actual tables of data, e.g. a
|
||||
-- sequence of tuples, like one would see in an SQL database. For these
|
||||
-- structures it's an obvious choice to align them based on the keys.
|
||||
-- 7. Pseudo-Tabular: Some structures are almost tabular, e.g. they are sequences
|
||||
-- of tuples, but some of the tuples differ in their structure. For these
|
||||
-- structures it's still useful to tabulate the keys that all tuples share. To
|
||||
-- do this we should sort the key order descending by the number of tuples with
|
||||
-- the key.
|
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-- But what do we do about the the outlier keys? We can either justify the
|
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-- entire table, and give specific spots for the outlier keys, thereby
|
||||
-- significantly increasing the size of the table, or we can leave the table
|
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-- unjustified, abandoning it's eye-guiding attributes.
|
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-- 8. Special cases: (Array-tree, Table-Tree, Linked-List, Predictive Sequences) TODO
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
-- Import files
|
||||
|
|
|
|||
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Reference in New Issue
Block a user