Parser-based font lock and other font lock mechanisms are not mutually
exclusive. By default, if enabled, parser-based font lock runs first,
-replacing syntactic font lock, then the regexp-based font lock.
+replacing syntactic font lock, followed by regexp-based font lock.
Although parser-based font lock doesn't share the same customization
variables with regexp-based font lock, it uses similar customization
For more information about queries, patterns, and capture names, see
@ref{Pattern Matching}.
-To setup tree-sitter fontification, a major mode should first set
+To set up tree-sitter fontification, a major mode should first set
@code{treesit-font-lock-settings} with the output of
@code{treesit-font-lock-rules}, then call
@code{treesit-major-mode-setup}.
This function takes a series of @var{query-spec}s, where each
@var{query-spec} is a @var{query} preceded by one or more
-@var{:keyword}/@var{value} pairs. Each @var{query} is a
-tree-sitter query in either the string, s-expression or compiled form.
+@var{keyword}/@var{value} pairs. Each @var{query} is a tree-sitter
+query in either the string, s-expression, or compiled form.
@c FIXME: Cross-ref treesit-font-lock-level to user manual.
-For each @var{query}, the @var{:keyword}/@var{value} pairs that
-precede it add meta information to it. The @code{:language} keyword
-declares @var{query}'s language. The @code{:feature} keyword sets the
-feature name of @var{query}. Users can control which features are
-enabled with @code{treesit-font-lock-level} and
+For each @var{query}, the @var{keyword}/@var{value} pairs that precede
+it add meta information to it. The @code{:language} keyword declares
+@var{query}'s language. The @code{:feature} keyword sets the feature
+name of @var{query}. Users can control which features are enabled
+with @code{treesit-font-lock-level} and
@code{treesit-font-lock-feature-list} (described below). These two
keywords are mandatory.
with that face.
@findex treesit-fontify-with-override
-Capture names can also be function names, in which case the function
+A capture name can also be a function name, in which case the function
is called with 4 arguments: @var{node} and @var{override}, @var{start}
and @var{end}, where @var{node} is the node itself, @var{override} is
-the override property of the rule which captured this node, and
-@var{start} and @var{end} limits the region in which this function
+the @code{:override} property of the rule which captured this node,
+and @var{start} and @var{end} limit the region which this function
should fontify. (If this function wants to respect the @var{override}
argument, it can use @code{treesit-fontify-with-override}.)
highlights whatever is being defined, e.g., the function name in a
function definition, the struct name in a struct definition, the
variable name in a variable definition; @code{assignment} highlights
-the whatever is being assigned to, e.g., the variable or field in an
+whatever is being assigned to, e.g., the variable or field in an
assignment statement; @code{key} highlights keys in key-value pairs,
-e.g., keys in a JSON object, or a Python dictionary; @code{doc}
+e.g., keys in a JSON object or Python dictionary; @code{doc}
highlights docstrings or doc-comments.
For example, the value of this variable could be:
to write a custom indentation function that queries the syntax tree
and indents accordingly for each language, but that is a lot of work.
It is more convenient to use the simple indentation engine described
-below: then the major mode needs only to write some indentation rules
+below: then the major mode needs only write some indentation rules,
and the engine takes care of the rest.
To enable the parser-based indentation engine, either set
@cindex indentation rules, for parser-based indentation
@defvar treesit-simple-indent-rules
-This local variable stores indentation rules for every language. It is
-a list of the form: @w{@code{(@var{language} . @var{rules})}}, where
-@var{language} is a language symbol, and @var{rules} is a list of the
-form @w{@code{(@var{matcher} @var{anchor} @var{offset})}}.
+This local variable stores indentation rules for every language. It
+is an alist with elements of the form @w{@code{(@var{language}
+. @var{rules})}}, where @var{language} is a language symbol, and
+@var{rules} is a list with elements of the form
+@w{@code{(@var{matcher} @var{anchor} @var{offset})}}.
First, Emacs passes the smallest tree-sitter node at the beginning of
the current line to @var{matcher}; if it returns non-@code{nil}, this
@defvar treesit-simple-indent-presets
This is a list of defaults for @var{matcher}s and @var{anchor}s in
-@code{treesit-simple-indent-rules}. Each of them represents a function
-that takes 3 arguments: @var{node}, @var{parent} and @var{bol}. The
-available default functions are:
+@code{treesit-simple-indent-rules}. Each of them represents a
+function that takes 3 arguments: @var{node}, @var{parent}, and
+@var{bol}. The available default functions are:
@ftable @code
@item no-node
This matcher is a function that is called with 3 arguments:
-@var{node}, @var{parent}, and @var{bol}, and returns non-@code{nil},
+@var{node}, @var{parent}, and @var{bol}. It returns non-@code{nil},
indicating a match, if @var{node} is @code{nil}, i.e., there is no
node that starts at @var{bol}. This is the case when @var{bol} is on
an empty line or inside a multi-line string, etc.
and @var{bol}, and returns non-@code{nil} if @var{node}'s type matches
regexp @var{type}.
+@item field-is
+This matcher is a function of one argument, @var{name}; it returns a
+function that is called with 3 arguments: @var{node}, @var{parent},
+and @var{bol}, and returns non-@code{nil} if @var{node}'s field name
+in @var{parent} matches regexp @var{name}.
+
@item query
This matcher is a function of one argument, @var{query}; it returns a
function that is called with 3 arguments: @var{node}, @var{parent},
@item comment-end
This matcher is a function that is called with 3 arguments:
@var{node}, @var{parent}, and @var{bol}, and returns non-@code{nil} if
-point is before a comment ending token. Comment ending tokens are
-defined by regular expression @code{comment-end-skip}
+point is before a comment-ending token. Comment-ending tokens are
+defined by regexp @code{comment-end-skip}.
+
+@item catch-all
+This matcher is a function that is called with 3 arguments:
+@var{node}, @var{parent}, and @var{bol}. It always returns
+non-@code{nil}, indicating a match.
@item first-sibling
This anchor is a function that is called with 3 arguments: @var{node},
@var{parent}, and @var{bol}, and returns the start of the first child
of @var{parent}.
+@item nth-sibling
+This anchor is a function of two arguments: @var{n}, and an optional
+argument @var{named}. It returns a function that is called with 3
+arguments: @var{node}, @var{parent}, and @var{bol}, and returns the
+start of the @var{n}th child of @var{parent}. If @var{named} is
+non-@code{nil}, only named children are counted (@pxref{tree-sitter
+named node, named node}).
+
@item parent
This anchor is a function that is called with 3 arguments: @var{node},
@var{parent}, and @var{bol}, and returns the start of @var{parent}.
+@item grand-parent
+This anchor is a function that is called with 3 arguments: @var{node},
+@var{parent}, and @var{bol}, and returns the start of @var{parent}'s
+parent.
+
+@item great-grand-parent
+This anchor is a function that is called with 3 arguments: @var{node},
+@var{parent}, and @var{bol}, and returns the start of @var{parent}'s
+parent's parent.
+
@item parent-bol
This anchor is a function that is called with 3 arguments: @var{node},
@var{parent}, and @var{bol}, and returns the first non-space character
on the line which @var{parent}'s start is on.
-@item parent-bol
+@item standalone-parent
This anchor is a function that is called with 3 arguments: @var{node},
@var{parent}, and @var{bol}. It finds the first ancestor node
-(parent, grandparent, etc) of @var{node} that starts on its own line,
-and return the start of that node. ``Starting on its own line'' means
-there is only whitespace character before the node on the line which
-the node's start is on.
+(parent, grandparent, etc.@:) of @var{node} that starts on its own
+line, and return the start of that node. ``Starting on its own line''
+means there is only whitespace character before the node on the line
+which the node's start is on.
@item prev-sibling
This anchor is a function that is called with 3 arguments: @var{node},
@item prev-adaptive-prefix
This anchor is a function that is called with 3 arguments: @var{node},
-@var{parent}, and @var{bol}. It tries to go to the beginning of the
-previous non-empty line, and matches @code{adaptive-fill-regexp}. If
-there is a match, this function returns the end of the match,
-otherwise it returns @code{nil}. However, if the current line begins
-with a prefix (e.g., ``-''), return the beginning of the prefix of the
-previous line instead, so that the two prefixes align. This anchor is
-useful for an @code{indent-relative}-like indent behavior for block
-comments.
+@var{parent}, and @var{bol}. It tries to match
+@code{adaptive-fill-regexp} to the text at the beginning of the
+previous non-empty line. If there is a match, this function returns
+the end of the match, otherwise it returns @code{nil}. However, if
+the current line begins with a prefix (e.g., @samp{-}), return the
+beginning of the prefix of the previous line instead, so that the two
+prefixes align. This anchor is useful for an
+@code{indent-relative}-like indent behavior for block comments.
@end ftable
@end defvar
Here are some utility functions that can help writing parser-based
indentation rules.
-@defun treesit-check-indent mode
-This function checks the current buffer's indentation against major
+@deffn Command treesit-check-indent mode
+This command checks the current buffer's indentation against major
mode @var{mode}. It indents the current buffer according to
@var{mode} and compares the results with the current indentation.
Then it pops up a buffer showing the differences. Correct
indentation (target) is shown in green color, current indentation is
shown in red color. @c Are colors customizable? faces?
-@end defun
+@end deffn
It is also helpful to use @code{treesit-inspect-mode} (@pxref{Language
Grammar}) when writing indentation rules.
Emacs provides various ways to parse program source text and produce a
@dfn{syntax tree}. In a syntax tree, text is no longer considered a
one-dimensional stream of characters, but a structured tree of nodes,
-where each node representing a piece of text. Thus, a syntax tree can
+where each node represents a piece of text. Thus, a syntax tree can
enable interesting features like precise fontification, indentation,
navigation, structured editing, etc.
In addition to those, Emacs also provides integration with
@uref{https://tree-sitter.github.io/tree-sitter, the tree-sitter
-library}) if support for it was compiled in. The tree-sitter library
-implements an incremental parser and has support from a wide range of
+library} if support for it was compiled in. The tree-sitter library
+implements an incremental parser and has support for a wide range of
programming languages.
@defun treesit-available-p
@vindex treesit-extra-load-path
@vindex treesit-load-language-error
-Tree-sitter language grammar are distributed as dynamic libraries.
+Tree-sitter language grammars are distributed as dynamic libraries.
In order to use a language grammar in Emacs, you need to make sure
that the dynamic library is installed on the system. Emacs looks for
-language grammar in several places, in the following order:
+language grammars in several places, in the following order:
@itemize @bullet
@item
This means that Emacs could not find in the library the expected function
that every language grammar library should export.
@item (version-mismatch @var{error-msg})
-This means that the version of language grammar library is incompatible
-with that of the tree-sitter library.
+This means that the version of the language grammar library is
+incompatible with that of the tree-sitter library.
@end table
@noindent
@defun treesit-language-available-p language &optional detail
This function returns non-@code{nil} if the language grammar for
-@var{language} exist and can be loaded.
+@var{language} exists and can be loaded.
If @var{detail} is non-@code{nil}, return @code{(t . nil)} when
@var{language} is available, and @code{(nil . @var{data})} when it's
@end example
to the list in the variable @code{treesit-load-name-override-list}, where
-@var{library-base-name} is the basename of the dynamic library's file name,
+@var{library-base-name} is the basename of the dynamic library's file name
(usually, @file{libtree-sitter-@var{language}}), and
@var{function-name} is the function provided by the library
(usually, @code{tree_sitter_@var{language}}). For example,
tree-sitter library. By default, it returns the latest ABI version
supported by the library, but if @var{min-compatible} is
non-@code{nil}, it returns the oldest ABI version which the library
-still can support. language grammar libraries must be built for
+still can support. Language grammar libraries must be built for
ABI versions between the oldest and the latest versions supported by
the tree-sitter library, otherwise the library will be unable to load
them.
@cindex explore tree-sitter syntax tree
@cindex inspection of tree-sitter parse tree nodes
-To aid in understanding the syntax of a language and in debugging of
-Lisp program that use the syntax tree, Emacs provides an ``explore''
-mode, which displays the syntax tree of the source in the current
-buffer in real time. Emacs also comes with an ``inspect mode'', which
-displays information of the nodes at point in the mode-line.
+To aid in understanding the syntax of a language and in debugging Lisp
+programs that use the syntax tree, Emacs provides an ``explore'' mode,
+which displays the syntax tree of the source in the current buffer in
+real time. Emacs also comes with an ``inspect mode'', which displays
+information of the nodes at point in the mode-line.
@deffn Command treesit-explore-mode
This mode pops up a window displaying the syntax tree of the source in
@heading Reading the grammar definition
@cindex reading grammar definition, tree-sitter
-Authors of language grammar define the @dfn{grammar} of a
+Authors of language grammars define the @dfn{grammar} of a
programming language, which determines how a parser constructs a
concrete syntax tree out of the program text. In order to use the
syntax tree effectively, you need to consult the @dfn{grammar file}.
homepage}.
The grammar definition is written in JavaScript. For example, the
-rule matching a @code{function_definition} node looks like
+rule matching a @code{function_definition} node may look like
@example
@group
@item choice(@var{rule1}, @var{rule2}, @dots{})
matches one of the rules in its arguments.
@item repeat(@var{rule})
-matches @var{rule} for @emph{zero or more} times.
+matches @var{rule} @emph{zero or more} times.
This is like the @samp{*} operator in regular expressions.
@item repeat1(@var{rule})
-matches @var{rule} for @emph{one or more} times.
+matches @var{rule} @emph{one or more} times.
This is like the @samp{+} operator in regular expressions.
@item optional(@var{rule})
-matches @var{rule} for @emph{zero or one} time.
+matches @var{rule} @emph{zero or one} times.
This is like the @samp{?} operator in regular expressions.
@item field(@var{name}, @var{rule})
assigns field name @var{name} to the child node matched by @var{rule}.
@item token.immediate(@var{rule})
Normally, grammar rules ignore preceding whitespace; this
changes @var{rule} to match only when there is no preceding
-whitespaces.
+whitespace.
@item prec(@var{n}, @var{rule})
gives @var{rule} the level-@var{n} precedence.
@item prec.left([@var{n},] @var{rule})
If that buffer is an indirect buffer, its base buffer is used instead.
That is, indirect buffers use their base buffer's parsers. If the
base buffer is narrowed, an indirect buffer might not be able to
-retrieve information of the portion of the buffer text that are
+retrieve information of the portion of the buffer text that is
invisible in the base buffer. Lisp programs should widen as necessary
should they want to use a parser in an indirect buffer.
@end defun
@vindex treesit-buffer-too-large
When a parser does parse, it checks for the size of the buffer.
-Tree-sitter can only handle buffer no larger than about 4GB. If the
+Tree-sitter can only handle buffers no larger than about 4GB@. If the
size exceeds that, Emacs signals the @code{treesit-buffer-too-large}
error with signal data being the buffer size.
though the text is not directly edited, it is deemed to be ``changed''
nevertheless.
-Emacs lets a Lisp program to register callback functions
-(a.k.a.@: @dfn{notifiers}) for this kind of changes. A notifier
-function takes two arguments: @var{ranges} and @var{parser}.
-@var{ranges} is a list of cons cells of the form @w{@code{(@var{start}
-. @var{end})}}, where @var{start} and @var{end} mark the start and the
-end positions of a range. @var{parser} is the parser issuing the
-notification.
+Emacs lets a Lisp program register callback functions (a.k.a.@:
+@dfn{notifiers}) for these kinds of changes. A notifier function
+takes two arguments: @var{ranges} and @var{parser}. @var{ranges} is a
+list of cons cells of the form @w{@code{(@var{start} . @var{end})}},
+where @var{start} and @var{end} mark the start and the end positions
+of a range. @var{parser} is the parser issuing the notification.
Every time a parser reparses a buffer, it compares the old and new
parse-tree, computes the ranges in which nodes have changed, and
@cindex get node, tree-sitter
@cindex terminology, for tree-sitter functions
-Here's some terminology and conventions we use when documenting
+Here are some terms and conventions we use when documenting
tree-sitter functions.
A node in a syntax tree spans some portion of the program text in the
A leaf node is a node that doesn't have any child nodes.
This function tries to return a node whose span covers @var{pos}: the
-node's beginning position is less or equal to @var{pos}, and the
-node's end position is greater or equal to @var{pos}.
+node's beginning position is less than or equal to @var{pos}, and the
+node's end position is greater than or equal to @var{pos}.
If no leaf node's span covers @var{pos} (e.g., @var{pos} is in the
whitespace between two leaf nodes), this function returns the first
is at or after @var{end}.
@emph{Beware:} calling this function on an empty line that is not
-inside any top-level construct (function definition, etc.) most
+inside any top-level construct (function definition, etc.@:) most
probably will give you the root node, because the root node is the
smallest node that covers that empty line. Most of the time, you want
to use @code{treesit-node-at} instead.
is the string text.
This function returns @code{nil} if there is no @var{n}'th child.
-@var{n} could be negative, e.g., @code{-1} represents the last child.
+@var{n} could be negative, e.g., @minus{}1 represents the last child.
@end defun
@defun treesit-node-children node &optional named
@cindex nodes, by field name
@cindex syntax tree nodes, by field name
-To make the syntax tree easier to analyze, many language grammar
+To make the syntax tree easier to analyze, many language grammars
assign @dfn{field names} to child nodes (@pxref{tree-sitter node field
name, field name}). For example, a @code{function_definition} node
could have a @code{declarator} node and a @code{body} node.
This function finds the @emph{smallest} descendant node of @var{node}
that spans the region of text between positions @var{beg} and
@var{end}. It is similar to @code{treesit-node-at}. If @var{named}
-is non-@code{nil}, it looks for smallest named child.
+is non-@code{nil}, it looks for the smallest named child.
@end defun
@heading Searching for node
Like @code{treesit-search-subtree}, this function also traverses the
parse tree and matches each node with @var{predicate} (except for
@var{start}), where @var{predicate} can be a regexp or a function.
-For a tree like the below where @var{start} is marked S, this function
-traverses as numbered from 1 to 12:
+For a tree like the one below where @var{start} is marked @samp{S},
+this function traverses as numbered from 1 to 12:
@example
@group
@end example
Note that this function doesn't traverse the subtree of @var{start},
-and it always traverse leaf nodes first, then upwards.
+and it always traverses leaf nodes first, before moving upwards.
Like @code{treesit-search-subtree}, this function only searches for
named nodes by default, but if @var{all} is non-@code{nil}, it
start positions greater than the end position of @var{start}.
In the tree shown above, @code{treesit-search-subtree} traverses node
-S (@var{start}) and nodes marked with @code{o}, where this function
-traverses the nodes marked with numbers. This function is useful for
-answering questions like ``what is the first node after @var{start} in
-the buffer that satisfies some condition?''
+@samp{S} (@var{start}) and nodes marked with @code{o}, where this
+function traverses the nodes marked with numbers. This function is
+useful for answering questions like ``what is the first node after
+@var{start} in the buffer that satisfies some condition?''
@end defun
@defun treesit-search-forward-goto node predicate &optional start backward all
progress in terms of buffer position: the start/end position of the
returned node is always greater than that of @var{node}.
-Arguments @var{predicate}, @var{backward} and @var{all} are the same
+Arguments @var{predicate}, @var{backward}, and @var{all} are the same
as in @code{treesit-search-forward}.
@end defun
It takes the subtree under @var{root}, and combs it so only the nodes
that match @var{predicate} are left. Like previous functions, the
@var{predicate} can be a regexp string that matches against each
-node's type, or a function that takes a node and return non-@code{nil}
-if it matches.
+node's type, or a function that takes a node and returns
+non-@code{nil} if it matches.
-For example, for a subtree on the left that consist of both numbers
-and letters, if @var{predicate} is ``letter only'', the returned tree
-is the one on the right.
+For example, given the subtree on the left that consists of both
+numbers and letters, if @var{predicate} is ``letter only'', the
+returned tree is the one on the right.
@example
@group
If @var{process-fn} is non-@code{nil}, instead of returning the
matched nodes, this function passes each node to @var{process-fn} and
-uses the returned value instead. If non-@code{nil}, @var{depth} is
-the number of levels to go down from @var{root}. If @var{depth} is
-@code{nil}, it defaults to 1000.
+uses the returned value instead. If non-@code{nil}, @var{depth}
+limits the number of levels to go down from @var{root}. If
+@var{depth} is @code{nil}, it defaults to 1000.
Each node in the returned tree looks like
@w{@code{(@var{tree-sitter-node} . (@var{child} @dots{}))}}. The
This function finds immediate children of @var{node} that satisfy
@var{predicate}.
-The @var{predicate} function takes a node as the argument and should
+The @var{predicate} function takes a node as argument and should
return non-@code{nil} to indicate that the node should be kept. If
-@var{named} is non-@code{nil}, this function only examines the named
+@var{named} is non-@code{nil}, this function only examines named
nodes.
@end defun
@defun treesit-parent-until node predicate &optional include-node
This function repeatedly finds the parents of @var{node}, and returns
the parent that satisfies @var{pred}, a function that takes a node as
-the argument and returns a boolean that indicates a match. If no
-parent satisfies @var{pred}, this function returns @code{nil}.
+argument and returns a boolean that indicates a match. If no parent
+satisfies @var{pred}, this function returns @code{nil}.
Normally this function only looks at the parents of @var{node} but not
@var{node} itself. But if @var{include-node} is non-@code{nil}, this
@defun treesit-parent-while node pred
This function goes up the tree starting from @var{node}, and keeps
doing so as long as the nodes satisfy @var{pred}, a function that
-takes a node as the argument. That is, this function returns the
-highest parent of @var{node} that still satisfies @var{pred}. Note
-that if @var{node} satisfies @var{pred} but its immediate parent
-doesn't, @var{node} itself is returned.
+takes a node as argument. That is, this function returns the highest
+parent of @var{node} that still satisfies @var{pred}. Note that if
+@var{node} satisfies @var{pred} but its immediate parent doesn't,
+@var{node} itself is returned.
@end defun
@defun treesit-node-top-level node &optional type
@cindex tree-sitter, live parsing node
@cindex live node, tree-sitter
A node is considered @dfn{live} if its parser is not deleted, and the
-buffer to which it belongs to is a live buffer (@pxref{Killing Buffers}).
+buffer to which it belongs is a live buffer (@pxref{Killing Buffers}).
@defun treesit-node-check node property
This function returns non-@code{nil} if @var{node} has the specified
@var{node}. It returns @code{nil} if there is no @var{n}'th child, or
the @var{n}'th child doesn't have a field name.
-Note that @var{n} counts both named and anonymous child. And @var{n}
-could be negative, e.g., @code{-1} represents the last child.
+Note that @var{n} counts both named and anonymous children, and
+@var{n} can be negative, e.g., @minus{}1 represents the last child.
@end defun
@defun treesit-node-child-count node &optional named
-This function finds the number of children of @var{node}. If
+This function returns the number of children of @var{node}. If
@var{named} is non-@code{nil}, it only counts named children
(@pxref{tree-sitter named node, named node}).
@end defun
@cindex query, tree-sitter
A @dfn{query} consists of multiple @dfn{patterns}. Each pattern is an
s-expression that matches a certain node in the syntax node. A
-pattern has the form @w{@code{(@var{type} (@var{child}@dots{}))}}
+pattern has the form @w{@code{(@var{type} (@var{child}@dots{}))}}.
For example, a pattern that matches a @code{binary_expression} node that
contains @code{number_literal} child nodes would look like
Now we can introduce the @dfn{query functions}.
@defun treesit-query-capture node query &optional beg end node-only
-This function matches patterns in @var{query} within @var{node}.
-The argument @var{query} can be either a string, a s-expression, or a
+This function matches patterns in @var{query} within @var{node}. The
+argument @var{query} can be either a string, an s-expression, or a
compiled query object. For now, we focus on the string syntax;
-s-expression syntax and compiled query are described at the end of the
-section.
+s-expression syntax and compiled queries are described at the end of
+the section.
The argument @var{node} can also be a parser or a language symbol. A
-parser means using its root node, a language symbol means find or
-create a parser for that language in the current buffer, and use the
-root node.
-
-The function returns all the captured nodes in a list of the form
-@w{@code{(@var{capture_name} . @var{node})}}. If @var{node-only} is
-non-@code{nil}, it returns the list of nodes instead. By default the
-entire text of @var{node} is searched, but if @var{beg} and @var{end}
-are both non-@code{nil}, they specify the region of buffer text where
-this function should match nodes. Any matching node whose span
-overlaps with the region between @var{beg} and @var{end} are captured,
-it doesn't have to be completely in the region.
+parser means use its root node, a language symbol means find or create
+a parser for that language in the current buffer, and use the root
+node.
+
+The function returns all the captured nodes in an alist with elements
+of the form @w{@code{(@var{capture_name} . @var{node})}}. If
+@var{node-only} is non-@code{nil}, it returns the list of @var{node}s
+instead. By default the entire text of @var{node} is searched, but if
+@var{beg} and @var{end} are both non-@code{nil}, they specify the
+region of buffer text where this function should match nodes. Any
+matching node whose span overlaps with the region between @var{beg}
+and @var{end} is captured; it doesn't have to be completely contained
+in the region.
@vindex treesit-query-error
@findex treesit-query-validate
@end example
@defun treesit-query-string string query language
-This function parses @var{string} with @var{language}, matches its
-root node with @var{query}, and returns the result.
+This function parses @var{string} as @var{language}, matches its root
+node with @var{query}, and returns the result.
@end defun
@heading More query syntax
-Besides node type and capture, tree-sitter's pattern syntax can
+Besides node type and capture name, tree-sitter's pattern syntax can
express anonymous node, field name, wildcard, quantification,
grouping, alternation, anchor, and predicate.
@subheading Wild card
In a pattern, @samp{(_)} matches any named node, and @samp{_} matches
-any named and anonymous node. For example, to capture any named child
+any named or anonymous node. For example, to capture any named child
of a @code{binary_expression} node, the pattern would be
@example
-(binary_expression (_) @@in_biexp)
+(binary_expression (_) @@in-biexp)
@end example
@subheading Field name
@end example
It is also possible to capture a node that doesn't have a certain
-field, say, a @code{function_definition} without a @code{body} field.
+field, say, a @code{function_definition} without a @code{body} field:
@example
(function_definition !body) @@func-no-body
@subheading Quantify node
@cindex quantify node, tree-sitter
-Tree-sitter recognizes quantification operators @samp{*}, @samp{+} and
-@samp{?}. Their meanings are the same as in regular expressions:
+Tree-sitter recognizes quantification operators @samp{*}, @samp{+},
+and @samp{?}. Their meanings are the same as in regular expressions:
@samp{*} matches the preceding pattern zero or more times, @samp{+}
-matches one or more times, and @samp{?} matches zero or one time.
+matches one or more times, and @samp{?} matches zero or one times.
For example, the following pattern matches @code{type_declaration}
-nodes that has @emph{zero or more} @code{long} keyword.
+nodes that have @emph{zero or more} @code{long} keywords.
@example
(type_declaration "long"*) @@long-type
@end example
-The following pattern matches a type declaration that has zero or one
-@code{long} keyword:
+The following pattern matches a type declaration that may or may not
+have a @code{long} keyword:
@example
(type_declaration "long"?) @@long-type
@subheading Grouping
-Similar to groups in regular expression, we can bundle patterns into
+Similar to groups in regular expressions, we can bundle patterns into
groups and apply quantification operators to them. For example, to
-express a comma separated list of identifiers, one could write
+express a comma-separated list of identifiers, one could write
@example
(identifier) ("," (identifier))*
@subheading Alternation
-Again, similar to regular expressions, we can express ``match anyone
-from this group of patterns'' in a pattern. The syntax is a list of
-patterns enclosed in square brackets. For example, to capture some
-keywords in C, the pattern would be
+Again, similar to regular expressions, we can express ``match any one
+of these patterns'' in a pattern. The syntax is a list of patterns
+enclosed in square brackets. For example, to capture some keywords in
+C, the pattern would be
@example
@group
@end example
@noindent
-tree-sitter only matches arrays where the first element equals to the
-last element. To attach a predicate to a pattern, we need to group
-them together. A predicate always starts with a @samp{#}. Currently
-there are three predicates, @code{#equal}, @code{#match}, and
-@code{#pred}.
+tree-sitter only matches arrays where the first element is equal to
+the last element. To attach a predicate to a pattern, we need to
+group them together. A predicate always starts with a @samp{#}.
+Currently there are three predicates: @code{#equal}, @code{#match},
+and @code{#pred}.
@deffn Predicate equal arg1 arg2
-Matches if @var{arg1} equals to @var{arg2}. Arguments can be either
+Matches if @var{arg1} is equal to @var{arg2}. Arguments can be either
strings or capture names. Capture names represent the text that the
captured node spans in the buffer.
@end deffn
@cindex tree-sitter patterns as sexps
@cindex patterns, tree-sitter, in sexp form
-Besides strings, Emacs provides a s-expression based syntax for
+Besides strings, Emacs provides an s-expression based syntax for
tree-sitter patterns. It largely resembles the string-based syntax.
For example, the following query
@end example
Most patterns can be written directly as strange but nevertheless
-valid s-expressions. Only a few of them needs modification:
+valid s-expressions. Only a few of them need modification:
@itemize
@item
@end example
@noindent
-is written in s-expression as
+is written in s-expression syntax as
@example
@group
need to be assigned different parsers. Traditionally, this is
achieved by using narrowing. While tree-sitter works with narrowing
(@pxref{tree-sitter narrowing, narrowing}), the recommended way is
-instead to set regions of buffer text (i.e., ranges) in which a parser
-will operate. This section describes functions for setting and
+instead to specify regions of buffer text (i.e., ranges) in which a
+parser will operate. This section describes functions for setting and
getting ranges for a parser.
Lisp programs should call @code{treesit-update-ranges} to make sure
@defun treesit-parser-set-included-ranges parser ranges
This function sets up @var{parser} to operate on @var{ranges}. The
@var{parser} will only read the text of the specified ranges. Each
-range in @var{ranges} is a list of the form @w{@code{(@var{beg}
+range in @var{ranges} is a pair of the form @w{@code{(@var{beg}
. @var{end})}}.
The ranges in @var{ranges} must come in order and must not overlap.
@heading Supporting multiple languages in Lisp programs
It should suffice for general Lisp programs to call the following two
-functions in order to support program sources that mixes multiple
+functions in order to support program sources that mix multiple
languages.
@defun treesit-update-ranges &optional beg end
embedded languages with that information, and then parses the embedded
languages.
-Take a buffer containing @acronym{HTML}, @acronym{CSS} and JavaScript
+Take a buffer containing @acronym{HTML}, @acronym{CSS}, and JavaScript
as an example. A Lisp program will first parse the whole buffer with
an @acronym{HTML} parser, then query the parser for
-@code{style_element} and @code{script_element} nodes, which
-correspond to @acronym{CSS} and JavaScript text, respectively. Then
-it sets the range of the @acronym{CSS} and JavaScript parser to the
-ranges in which their corresponding nodes span.
+@code{style_element} and @code{script_element} nodes, which correspond
+to @acronym{CSS} and JavaScript text, respectively. Then it sets the
+range of the @acronym{CSS} and JavaScript parsers to the range which
+their corresponding nodes span.
Given a simple @acronym{HTML} document:
@example
@group
-(setq-local treesit-range-settings
- (treesit-range-rules
- :embed 'javascript
- :host 'html
- '((script_element (raw_text) @@capture))
+(setq treesit-range-settings
+ (treesit-range-rules
+ :embed 'javascript
+ :host 'html
+ '((script_element (raw_text) @@capture))
@end group
@group
- :embed 'css
- :host 'html
- '((style_element (raw_text) @@capture))))
+ :embed 'css
+ :host 'html
+ '((style_element (raw_text) @@capture))))
@end group
@end example
It takes a series of @var{query-spec}s, where each @var{query-spec} is
a @var{query} preceded by zero or more @var{keyword}/@var{value}
-pairs. Each @var{query} is a tree-sitter query in either the
-string, s-expression or compiled form, or a function.
+pairs. Each @var{query} is a tree-sitter query in either the string,
+s-expression, or compiled form, or a function.
If @var{query} is a tree-sitter query, it should be preceded by two
-@var{:keyword}/@var{value} pairs, where the @code{:embed} keyword
+@var{keyword}/@var{value} pairs, where the @code{:embed} keyword
specifies the embedded language, and the @code{:host} keyword
-specified the host language.
+specifies the host language.
@code{treesit-update-ranges} uses @var{query} to figure out how to set
the ranges for parsers for the embedded language. It queries
-@var{query} in a host language parser, computes the ranges in which
-the captured nodes span, and applies these ranges to embedded
-language parsers.
+@var{query} in a host language parser, computes the ranges which the
+captured nodes span, and applies these ranges to embedded language
+parsers.
-If @var{query} is a function, it doesn't need any @var{:keyword} and
+If @var{query} is a function, it doesn't need any @var{keyword} and
@var{value} pair. It should be a function that takes 2 arguments,
@var{start} and @var{end}, and sets the ranges for parsers in the
current buffer in the region between @var{start} and @var{end}. It is
@code{treesit-ready-p} automatically emits a warning if conditions for
enabling tree-sitter aren't met.
-If a tree-sitter major mode shares setup with their ``native''
-counterpart, they can create a ``base mode'' that contains the common
+If a tree-sitter major mode shares setup with its ``native''
+counterpart, one can create a ``base mode'' that contains the common
setup, like this:
@example
@defun treesit-ready-p language &optional quiet
This function checks for conditions for activating tree-sitter. It
checks whether Emacs was built with tree-sitter, whether the buffer's
-size is not too large for tree-sitter to handle it, and whether the
-language grammar for @var{language} is available on the system
-(@pxref{Language Grammar}).
+size is not too large for tree-sitter to handle, and whether the
+grammar for @var{language} is available on the system (@pxref{Language
+Grammar}).
This function emits a warning if tree-sitter cannot be activated. If
@var{quiet} is @code{message}, the warning is turned into a message;
@end itemize
@end defun
-For more information of these built-in tree-sitter features,
+For more information on these built-in tree-sitter features,
@pxref{Parser-based Font Lock}, @pxref{Parser-based Indentation}, and
@pxref{List Motion}.
@defvar treesit-defun-name-function
If non-@code{nil}, this variable's value should be a function that is
called with a node as its argument, and returns the defun name of the
-node. The function should have the same semantic as
+node. The function should have the same semantics as
@code{treesit-defun-name}: if the node is not a defun node, or the
node is a defun node but doesn't have a name, or the node is
@code{nil}, it should return @code{nil}.
@end defvar
-@defvar treesit-defun-type-regexp
-This variable determines which nodes are considered defuns by Emacs.
-It can be a regexp that matches the type of defun nodes.
-
-Sometimes not all nodes matched by the regexp are valid defuns.
-Therefore, this variable can also be a cons cell of the form
-@w{(@var{regexp} . @var{pred})}, where @var{pred} should be a function
-that takes a node as its argument, and returns @code{t} if the node is
-valid defun, or @code{nil} if it is not valid.
-@end defvar
-
@node Tree-sitter C API
@section Tree-sitter C API Correspondence
Emacs' tree-sitter integration doesn't expose every feature
-provided by tree-sitter's C API. Missing features include:
+provided by tree-sitter's C API@. Missing features include:
@itemize
@item
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