README.md - third_party/verible - Git at Google

 # Verible

 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 [![Continuous Integration](https://github.com/google/verible/workflows/verible-ci/badge.svg)](https://github.com/google/verible/actions/workflows/verible-ci.yml)

 <!--*
 freshness: { owner: 'hzeller' reviewed: '2020-10-08' }
 *-->

 The Verible project's main mission is to parse SystemVerilog (IEEE 1800-2017)
 (as standardized in the [SV-LRM]) for a wide variety of applications, including
 developer tools.

 It was born out of a need to parse *un-preprocessed* source files, which is
 suitable for single-file applications like style-linting and formatting. In
 doing so, it can be adapted to parse *preprocessed* source files, which is what
 real compilers and toolchains require.

 The spirit of the project is that no-one should ever have to develop a
 SystemVerilog parser for their own application, because developing a
 standard-compliant parser is an enormous task due to the syntactic complexity of
 the language. Verible's parser is also regularly tested against an ever-growing
 suite of (tool-independent) language compliance tests at
 https://symbiflow.github.io/sv-tests/.

 A lesser (but notable) objective is that the language-agnostic components of
 Verible be usable for rapidly developing language support tools for other
 languages.

 ## Developers, Welcome

 For source code browsing, we recommend using the fully-indexed and searchable
 mirror at https://cs.opensource.google/verible/verible.

 If you'd like to contribute, check out the [contributing](./CONTRIBUTING.md)
 guide and the [development resources](./doc/development.md).

 ## Build

 Verible's code base is written in C++.

 To build, you need the [bazel] build system and a C++17 compatible compiler
 (e.g. >= g++-9).

 ```bash
 # Build all tools and libraries
 bazel build -c opt //...
 ```

 You can access the generated artifacts under `bazel-bin/`. For instance the
 syntax checker will be at
 `bazel-bin/verilog/tools/syntax/verible-verilog-syntax` (corresponding to the
 target name `//verilog/tools/syntax:verible-verilog-syntax`).

 ### Installation

 For simple installation, we provide regular [binary releases].

 If you prefer to build and install the binaries locally yourself:

 ```bash
 # In your home directory
 bazel run -c opt :install -- ~/bin

 # For a system directory that requires root-access, call with -s option.
 # (Do _not_ run bazel with sudo.)
 bazel run -c opt :install -- -s /usr/local/bin
 ```

 ### Test

 We strongly encourage running the test suite using [bazel]:

 ```bash
 # Run all tests
 bazel test -c opt //...
 ```

 ## Mailing Lists

 Join the Verible community!

 *   Developers: verible-dev@googlegroups.com
     ([join](https://groups.google.com/forum/#!forum/verible-dev/join))
 *   Users: verible-users@googlegroups.com
     ([join](https://groups.google.com/forum/#!forum/verible-users/join))

 ## SystemVerilog Developer Tools

 ### Parser

 [Learn more about the parser implementation here](./verilog/parser).

 We provide a standalone [`verible-verilog-syntax`](./verilog/tools/syntax) tool
 to help with visualizing the syntax structure as understood by the lexer and
 parser. This is very useful tor troubleshooting and understand the internal
 representations seen by the other tools.

 The tool has an ability of exporting a concrete syntax tree in JSON format,
 making use of it in external tools easy. There is also a
 [Python wrapper module and a few example scripts](./verilog/tools/syntax/export_json_examples).

 ### Style Linter

 [`verible-verilog-lint`](./verilog/tools/lint) identifies constructs or patterns
 in code that are deemed undesirable according to a style guide. The main goal is
 to relieve humans the burden of reviewing code for style compliance. Many
 [lint rules][lint-rule-list] use syntax tree pattern matching to find style
 violations.

 Features:

 *   Style guide citations in diagnostics
 *   Rule deck configurability
 *   Waiver mechanisms: in-file, external waiver file

 Documentation:

 *   [Style linter user documentation](./verilog/tools/lint)
 *   [Generated lint rule documentation][lint-rule-list]

 ### Formatter

 The [`verible-verilog-format`](./verilog/tools/formatter) formatter manages
 whitespace in accordance with a particular style. The main goal is to relieve
 humans of having to manually manage whitespace, wrapping, and indentation, and
 to provide a tool that can be integrated into any editor to enable
 editor-independent consistency.

 Features (various degress of work-in-progress):

 *   Corrects indentation
 *   Corrects inter-token spacing, with syntax context awareness
 *   Line-wrapping to a column limit
 *   Support for incremental formatting, only touched changed lines.
 *   Interactive formatting: accept or decline formatting changes
 *   Tabular alignment

 <!--
 TODO(fangism): a demo GIF animation here.
 See https://github.com/google/verible/issues/528
 -->

 ### Lexical Diff

 [`verible-verilog-diff`](./verilog/tools/diff) compares two input files for
 equivalence.

 ### Verible project tool

 [`verible-verilog-project`](./verilog/tools/project) is a multi-tool that
 operates on whole Verilog projects, consisting of a file list and related
 configurations. This serves as a diagnostic tool for analyzing (and potentially
 transforming) project-level sources.

 ### Code Obfuscator

 [`verible-verilog-obfuscate`](./verilog/tools/obfuscator) transforms Verilog
 code by replacing identifiers with obfuscated names of equal length, and
 preserving all other text, including spaces. Output is written to stdout. The
 resulting file size is the same as the original. This is useful for preparing
 potentially sensitive test cases with tool vendors.

 <!--
 TODO(fangism): a short demo GIF animation here.
 See https://github.com/google/verible/issues/528
 -->

 ### Preprocessor

 [`verible-verilog-preprocessor`](./verilog/tools/preprocessor) is a collection
 of preprocessor-like tools, (but does not include a fully-featured Verilog
 preprocessor yet.)

 ### Source Code Indexer

 [`verible-verilog-kythe-extractor`](./verilog/tools/kythe) extracts indexing
 facts fromm SV source code using the [Kythe](http://kythe.io) schema, which can
 then enhance IDEs with linked cross-references for ease of source code
 navigation.

 <!--
 TODO(minatoma): short animation of hover/navigation features
 -->

 ### Future Intent

 The Verible team is interested in exploring how it can help other tool
 developers in providing a SystemVerilog front end, for example, emitting an
 abstract syntax tree (AST). If you are interested in collaborating, contact us.

 [bazel]: https://bazel.build/
 [SV-LRM]: https://ieeexplore.ieee.org/document/8299595
 [lint-rule-list]: https://google.github.io/verible/lint.html
 [lint-rule-list_enum-name-style]: https://google.github.io/verible/lint.html#enum-name-style
 [lint-rule-list_line-length]: https://google.github.io/verible/lint.html#line-length
 [lint-rule-list_no-tabs]: https://google.github.io/verible/lint.html#no-tabs
 [binary releases]: https://github.com/google/verible/releases
	# Verible

	[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
	[![Continuous Integration](https://github.com/google/verible/workflows/verible-ci/badge.svg)](https://github.com/google/verible/actions/workflows/verible-ci.yml)

	<!--*
	freshness: { owner: 'hzeller' reviewed: '2020-10-08' }
	*-->

	The Verible project's main mission is to parse SystemVerilog (IEEE 1800-2017)
	(as standardized in the [SV-LRM]) for a wide variety of applications, including
	developer tools.

	It was born out of a need to parse un-preprocessed source files, which is
	suitable for single-file applications like style-linting and formatting. In
	doing so, it can be adapted to parse preprocessed source files, which is what
	real compilers and toolchains require.

	The spirit of the project is that no-one should ever have to develop a
	SystemVerilog parser for their own application, because developing a
	standard-compliant parser is an enormous task due to the syntactic complexity of
	the language. Verible's parser is also regularly tested against an ever-growing
	suite of (tool-independent) language compliance tests at
	https://symbiflow.github.io/sv-tests/.

	A lesser (but notable) objective is that the language-agnostic components of
	Verible be usable for rapidly developing language support tools for other
	languages.

	## Developers, Welcome

	For source code browsing, we recommend using the fully-indexed and searchable
	mirror at https://cs.opensource.google/verible/verible.

	If you'd like to contribute, check out the [contributing](./CONTRIBUTING.md)
	guide and the [development resources](./doc/development.md).

	## Build

	Verible's code base is written in C++.

	To build, you need the [bazel] build system and a C++17 compatible compiler
	(e.g. >= g++-9).

	```bash
	# Build all tools and libraries
	bazel build -c opt //...
	```

	You can access the generated artifacts under `bazel-bin/`. For instance the
	syntax checker will be at
	`bazel-bin/verilog/tools/syntax/verible-verilog-syntax` (corresponding to the
	target name `//verilog/tools/syntax:verible-verilog-syntax`).

	### Installation

	For simple installation, we provide regular [binary releases].

	If you prefer to build and install the binaries locally yourself:

	```bash
	# In your home directory
	bazel run -c opt :install -- ~/bin

	# For a system directory that requires root-access, call with -s option.
	# (Do _not_ run bazel with sudo.)
	bazel run -c opt :install -- -s /usr/local/bin
	```

	### Test

	We strongly encourage running the test suite using [bazel]:

	```bash
	# Run all tests
	bazel test -c opt //...
	```

	## Mailing Lists

	Join the Verible community!

	* Developers: verible-dev@googlegroups.com
	([join](https://groups.google.com/forum/#!forum/verible-dev/join))
	* Users: verible-users@googlegroups.com
	([join](https://groups.google.com/forum/#!forum/verible-users/join))

	## SystemVerilog Developer Tools

	### Parser

	[Learn more about the parser implementation here](./verilog/parser).

	We provide a standalone [`verible-verilog-syntax`](./verilog/tools/syntax) tool
	to help with visualizing the syntax structure as understood by the lexer and
	parser. This is very useful tor troubleshooting and understand the internal
	representations seen by the other tools.

	The tool has an ability of exporting a concrete syntax tree in JSON format,
	making use of it in external tools easy. There is also a
	[Python wrapper module and a few example scripts](./verilog/tools/syntax/export_json_examples).

	### Style Linter

	[`verible-verilog-lint`](./verilog/tools/lint) identifies constructs or patterns
	in code that are deemed undesirable according to a style guide. The main goal is
	to relieve humans the burden of reviewing code for style compliance. Many
	[lint rules][lint-rule-list] use syntax tree pattern matching to find style
	violations.

	Features:

	* Style guide citations in diagnostics
	* Rule deck configurability
	* Waiver mechanisms: in-file, external waiver file

	Documentation:

	* [Style linter user documentation](./verilog/tools/lint)
	* [Generated lint rule documentation][lint-rule-list]

	### Formatter

	The [`verible-verilog-format`](./verilog/tools/formatter) formatter manages
	whitespace in accordance with a particular style. The main goal is to relieve
	humans of having to manually manage whitespace, wrapping, and indentation, and
	to provide a tool that can be integrated into any editor to enable
	editor-independent consistency.

	Features (various degress of work-in-progress):

	* Corrects indentation
	* Corrects inter-token spacing, with syntax context awareness
	* Line-wrapping to a column limit
	* Support for incremental formatting, only touched changed lines.
	* Interactive formatting: accept or decline formatting changes
	* Tabular alignment

	<!--
	TODO(fangism): a demo GIF animation here.
	See https://github.com/google/verible/issues/528
	-->

	### Lexical Diff

	[`verible-verilog-diff`](./verilog/tools/diff) compares two input files for
	equivalence.

	### Verible project tool

	[`verible-verilog-project`](./verilog/tools/project) is a multi-tool that
	operates on whole Verilog projects, consisting of a file list and related
	configurations. This serves as a diagnostic tool for analyzing (and potentially
	transforming) project-level sources.

	### Code Obfuscator

	[`verible-verilog-obfuscate`](./verilog/tools/obfuscator) transforms Verilog
	code by replacing identifiers with obfuscated names of equal length, and
	preserving all other text, including spaces. Output is written to stdout. The
	resulting file size is the same as the original. This is useful for preparing
	potentially sensitive test cases with tool vendors.

	<!--
	TODO(fangism): a short demo GIF animation here.
	See https://github.com/google/verible/issues/528
	-->

	### Preprocessor

	[`verible-verilog-preprocessor`](./verilog/tools/preprocessor) is a collection
	of preprocessor-like tools, (but does not include a fully-featured Verilog
	preprocessor yet.)

	### Source Code Indexer

	[`verible-verilog-kythe-extractor`](./verilog/tools/kythe) extracts indexing
	facts fromm SV source code using the [Kythe](http://kythe.io) schema, which can
	then enhance IDEs with linked cross-references for ease of source code
	navigation.

	<!--
	TODO(minatoma): short animation of hover/navigation features
	-->

	### Future Intent

	The Verible team is interested in exploring how it can help other tool
	developers in providing a SystemVerilog front end, for example, emitting an
	abstract syntax tree (AST). If you are interested in collaborating, contact us.

	[bazel]: https://bazel.build/
	[SV-LRM]: https://ieeexplore.ieee.org/document/8299595
	[lint-rule-list]: https://google.github.io/verible/lint.html
	[lint-rule-list_enum-name-style]: https://google.github.io/verible/lint.html#enum-name-style
	[lint-rule-list_line-length]: https://google.github.io/verible/lint.html#line-length
	[lint-rule-list_no-tabs]: https://google.github.io/verible/lint.html#no-tabs
	[binary releases]: https://github.com/google/verible/releases