Nvim documentation: treesitter

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*treesitter.txt*    Nvim


Tree-sitter integration					*treesitter*

                                      Type |gO| to see the table of contents.


VIM.TREESITTER						*lua-treesitter*

Nvim integrates the tree-sitter library for incremental parsing of buffers.

Currently Nvim does not provide the tree-sitter parsers, instead these must
be built separately, for instance using the tree-sitter utility. The only
exception is a C parser being included in official builds for testing
purposes. Parsers are searched for as `parser/{lang}.*` in any 'runtimepath'
directory. A parser can also be loaded manually using a full path:

    vim.treesitter.require_language("python", "/path/to/python.so")

 Create a parser for a buffer and a given language (if another plugin uses the
same buffer/language combination, it will be safely reused). Use

    parser = vim.treesitter.get_parser(bufnr, lang)

 `bufnr=0` can be used for current buffer. `lang` will default to 'filetype'  (this
doesn't work yet for some filetypes like "cpp") Currently, the parser will be
retained for the lifetime of a buffer but this is subject to change. A plugin
should keep a reference to the parser object as long as it wants incremental

To check which language version is compiled with neovim, the number is stored
within `vim.treesitter.language_version`. This number is not too helpful
unless you are wondering about compatibility between different versions of
compiled grammars.

Parser files						*treesitter-parsers*

Parsers are the heart of tree-sitter. They are libraries that tree-sitter will
search for in the `parser` runtime directory.

For a parser to be available for a given language, there must be a file named
`{lang}.so` within the parser directory.

Parser methods						*lua-treesitter-parser*

tsparser:parse()					*tsparser:parse()*
Whenever you need to access the current syntax tree, parse the buffer:

    tstree = parser:parse()

 This will return a table of immutable trees that represent the current state of the
buffer. When the plugin wants to access the state after a (possible) edit
it should call `parse()` again. If the buffer wasn't edited, the same tree will
be returned again without extra work. If the buffer was parsed before,
incremental parsing will be done of the changed parts.

NB: to use the parser directly inside a |nvim_buf_attach| Lua callback, you must
call `get_parser()` before you register your callback. But preferably parsing
shouldn't be done directly in the change callback anyway as they will be very
frequent. Rather a plugin that does any kind of analysis on a tree should use
a timer to throttle too frequent updates.

tsparser:set_included_regions({region_list})			*tsparser:set_included_regions()*
	Changes the regions the parser should consider. This is used for
	language injection.  {region_list} should be of the form (all zero-based):
		{node1, node2},
	`node1` and `node2` are both considered part of the same region and
	will be parsed together with the parser in the same context.

Tree methods						*lua-treesitter-tree*

tstree:root()						*tstree:root()*
	Return the root node of this tree.

tstree:copy()						*tstree:copy()*
	Returns a copy of the `tstree`.

Node methods						*lua-treesitter-node*

tsnode:parent()						*tsnode:parent()*
	Get the node's immediate parent.

tsnode:iter_children()					*tsnode:iter_children()*
	Iterates over all the direct children of {tsnode}, regardless of
	wether they are named or not.
	Returns the child node plus the eventual field name corresponding to
	this child node.

tsnode:field({name})					*tsnode:field()*
	Returns a table of the nodes corresponding to the {name} field.

tsnode:child_count()					*tsnode:child_count()*
	Get the node's number of children.

tsnode:child({index})						*tsnode:child()*
	Get the node's child at the given {index}, where zero represents the
	first child.

tsnode:named_child_count()			*tsnode:named_child_count()*
	Get the node's number of named children.

tsnode:named_child({index})					*tsnode:named_child()*
	Get the node's named child at the given {index}, where zero represents
	the first named child.

tsnode:start()						*tsnode:start()*
	Get the node's start position. Return three values: the row, column
	and total byte count (all zero-based).

tsnode:end_()						*tsnode:end_()*
	Get the node's end position. Return three values: the row, column
	and total byte count (all zero-based).

tsnode:range()						*tsnode:range()*
	Get the range of the node. Return four values: the row, column
	of the start position, then the row, column of the end position.

tsnode:type()						*tsnode:type()*
	Get the node's type as a string.

tsnode:symbol()						*tsnode:symbol()*
	Get the node's type as a numerical id.

tsnode:named()						*tsnode:named()*
	Check if the node is named. Named nodes correspond to named rules in
	the  grammar, whereas anonymous nodes correspond to string literals
	in the grammar.

tsnode:missing()					*tsnode:missing()*
	Check if the node is missing. Missing nodes are inserted by the
	parser in order to recover from certain kinds of syntax errors.

tsnode:has_error()					*tsnode:has_error()*
	Check if the node is a syntax error or contains any syntax errors.

tsnode:sexpr()						*tsnode:sexpr()*
	Get an S-expression representing the node as a string.

tsnode:id()							*tsnode:id()*
	Get an unique identier for the node inside its own tree.

	No guarantees are made about this identifer's internal representation,
	except for being a primitive lua type with value equality (so not a table).
	Presently it is a (non-printable) string.

	NB: the id is not guaranteed to be unique for nodes from different trees.

tsnode:descendant_for_range({start_row}, {start_col}, {end_row}, {end_col})

	Get the smallest node within this node that spans the given range of
	(row, column) positions

tsnode:named_descendant_for_range({start_row}, {start_col}, {end_row}, {end_col})

	Get the smallest named node within this node that spans the given
	range of (row, column) positions

Query methods						*lua-treesitter-query*

Tree-sitter queries are supported, with some limitations. Currently, the only
supported match predicate is `eq?` (both comparing a capture against a string
and two captures against each other).

A `query` consists of one or more patterns. A `pattern` is defined over node
types in the syntax tree.  A `match` corresponds to specific elements of the
syntax tree which match a pattern. Patterns may optionally define captures
and predicates. A `capture` allows you to associate names with a specific
node in a pattern. A `predicate` adds arbitrary metadata and conditional data
to a match.

vim.treesitter.parse_query({lang}, {query})

	Parse {query} as a string. (If the query is in a file, the caller
        should read the contents into a string before calling).

	Returns a `Query` (see |lua-treesitter-query|) object which can be used to
	search nodes in the syntax tree for the patterns defined in {query}
	using `iter_*` methods below. Exposes `info` and `captures` with
	additional information about the {query}.
	  - `captures` contains the list of unique capture names defined in
	  -` info.captures` also points to `captures`.
	  - `info.patterns` contains information about predicates.

query:iter_captures({node}, {bufnr}, {start_row}, {end_row})

	Iterate over all captures from all matches inside {node}.
	{bufnr} is needed if the query contains predicates, then the caller
	must ensure to use a freshly parsed tree consistent with the current
	text of the buffer. {start_row} and {end_row} can be used to limit
	matches inside a row range (this is typically used with root node
	as the node, i e to get syntax highlight matches in the current
	viewport). When omitted the start and end row values are used from
        the given node.

	The iterator returns three values, a numeric id identifying the capture,
	the captured node, and metadata from any directives processing the match.
	The following example shows how to get captures by name:

	for id, node, metadata in query:iter_captures(tree:root(), bufnr, first, last) do
	  local name = query.captures[id] -- name of the capture in the query
	  -- typically useful info about the node:
	  local type = node:type() -- type of the captured node
	  local row1, col1, row2, col2 = node:range() -- range of the capture
	  ... use the info here ...
query:iter_matches({node}, {bufnr}, {start_row}, {end_row})

	Iterate over all matches within a node. The arguments are the same as
	for |query:iter_captures()| but the iterated values are different:
	an (1-based) index of the pattern in the query, a table mapping
	capture indices to nodes, and metadata from any directives processing the match.
	If the query has more than one pattern the capture table might be sparse,
	and e.g. `pairs()` method should be used over `ipairs`.
	Here an example iterating over all captures in every match:

	for pattern, match, metadata in cquery:iter_matches(tree:root(), bufnr, first, last) do
	  for id, node in pairs(match) do
	    local name = query.captures[id]
	    -- `node` was captured by the `name` capture in the match

	    local node_data = metadata[id] -- Node level metadata

	    ... use the info here ...

Treesitter Query Predicates				*lua-treesitter-predicates*

When writing queries for treesitter, one might use `predicates`, that is,
special scheme nodes that are evaluted to verify things on a captured node for
example, the |eq?| predicate :
	((identifier) @foo (#eq? @foo "foo"))

This will only match identifier corresponding to the `"foo"` text.
Here is a list of built-in predicates :

	`eq?`						*ts-predicate-eq?*
		This predicate will check text correspondance between nodes or
		strings :
			((identifier) @foo (#eq? @foo "foo"))
			((node1) @left (node2) @right (#eq? @left @right))

	`match?`					*ts-predicate-match?*

	`vim-match?`					*ts-predicate-vim-match?*
		This will match if the provived vim regex matches the text
		corresponding to a node :
			((idenfitier) @constant (#match? @constant "^[A-Z_]+$"))
 		Note: the `^` and `$` anchors will respectively match the
			start and end of the node's text.

	`lua-match?`					*ts-predicate-lua-match?*
		This will match the same way than |match?| but using lua

	`contains?`					*ts-predicate-contains?*
		Will check if any of the following arguments appears in the
		text corresponding to the node :
			((identifier) @foo (#contains? @foo "foo"))
			((identifier) @foo-bar (#contains @foo-bar "foo" "bar"))

Each predicate has a `not-` prefixed predicate that is just the negation of
the predicate.

Treesitter Query Directive				*lua-treesitter-directives*

Treesitter queries can also contain `directives`. Directives store metadata for a node
or match and perform side effects. for example, the |set!| predicate sets metadata on
the match or node :
	((identifier) @foo (#set! "type" "parameter"))

Here is a list of built-in directives:

	`set!`						*ts-directive-set!*
		Sets key/value metadata for a specific node or match :
			((identifier) @foo (#set! @foo "kind" "parameter"))
			((node1) @left (node2) @right (#set! "type" "pair"))

	`offset!`					*ts-predicate-offset!*
		Takes the range of the captured node and applies the offsets
		to it's range :
			((idenfitier) @constant (#offset! @constant 0 1 0 -1))
 		This will generate a range object for the captured node with the
		offsets applied. The arguments are
		`({capture_id}, {start_row}, {start_col}, {end_row}, {end_col}, {key?})`
		The default key is "offset".

vim.treesitter.query.add_predicate({name}, {handler})

This adds a predicate with the name {name} to be used in queries.
{handler} should be a function whose signature will be :
	handler(match, pattern, bufnr, predicate)


This lists the currently available predicates to use in queries.

vim.treesitter.query.add_directive({name}, {handler})

This adds a directive with the name {name} to be used in queries.
{handler} should be a function whose signature will be :
	handler(match, pattern, bufnr, predicate, metadata)
Handlers can set match level data by setting directly on the metadata object `metadata.key = value`
Handlers can set node level data by using the capture id on the metadata table
`metadata[capture_id].key = value`

Treesitter syntax highlighting (WIP)			*lua-treesitter-highlight*

NOTE: This is a partially implemented feature, and not usable as a default
solution yet. What is documented here is a temporary interface intended
for those who want to experiment with this feature and contribute to
its development.

Highlights are defined in the same query format as in the tree-sitter highlight
crate, which some limitations and additions. Set a highlight query for a
buffer with this code:

    local query = [[
      "for" @keyword
      "if" @keyword
      "return" @keyword

      (string_literal) @string
      (number_literal) @number
      (comment) @comment

      (preproc_function_def name: (identifier) @function)

      ; ... more definitions

    highlighter = vim.treesitter.TSHighlighter.new(query, bufnr, lang)
    -- alternatively, to use the current buffer and its filetype:
    -- highlighter = vim.treesitter.TSHighlighter.new(query)

    -- Don't recreate the highlighter for the same buffer, instead
    -- modify the query like this:
    local query2 = [[ ... ]]

As mentioned above the supported predicate is currently only `eq?`. `match?`
predicates behave like matching always fails. As an addition a capture which
begin with an upper-case letter like `@WarningMsg` will map directly to this
highlight group, if defined. Also if the predicate begins with upper-case and
contains a dot only the part before the first will be interpreted as the
highlight group. As an example, this warns of a binary expression with two
identical identifiers, highlighting both as YXXYhl-WarningMsg|:

    ((binary_expression left: (identifier) @WarningMsg.left right: (identifier) @WarningMsg.right)
     (eq? @WarningMsg.left @WarningMsg.right))

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