Selector (tw.tw.css.Css.Selector)

Shared selector types exposed by both implementation and interface.

type attribute_match =

| Presence
| Exact of string
| Whitespace_list of string
| Hyphen_list of string
| Prefix of string
| Suffix of string
| Substring of string

type combinator =

| Descendant
| Child
| Next_sibling
| Subsequent_sibling
| Column

type ns =

| Any
| None
| Prefix of string

type attr_flag =

| Case_insensitive
| Case_sensitive

type aria_attr =

| Busy
| Checked
| Disabled
| Expanded
| Hidden
| Pressed
| Readonly
| Required
| Selected
| Custom of string
(*
For aria-custom arbitrary values
*)

ARIA attribute names for type-safe handling

type attr_name =

| Aria of aria_attr
(*
aria-* attributes
*)
| Data of string
(*
data-* attributes
*)
| Regular of string
(*
All other attributes (class, type, etc.)
*)

Structured attribute names

type nth =

| Odd
| Even
| Index of int
| An_plus_b of int * int

type t =

| Element of ns option * string
| Class of string
| Id of string
| Universal of ns option
| Attribute of ns option * attr_name * attribute_match * attr_flag option
| Hover
| Active
| Focus
| Focus_visible
| Focus_within
| Target
| Link
| Visited
| Any_link
| Local_link
| Target_within
| Scope
| Root
| Empty
| First_child
| Last_child
| Only_child
| First_of_type
| Last_of_type
| Only_of_type
| Enabled
| Disabled
| Read_only
| Read_write
| Placeholder_shown
| Default
| Checked
| Indeterminate
| Blank
| Valid
| Invalid
| In_range
| Out_of_range
| Required
| Optional
| User_invalid
| User_valid
| Autofill
| Fullscreen
| Modal
| Picture_in_picture
| Left
| Right
| First
| Defined
| Playing
| Paused
| Seeking
| Buffering
| Stalled
| Muted
| Volume_locked
| Future
| Past
| Current
| Popover_open
| Before
| After
| First_letter
| First_line
| Backdrop
| Marker
| Placeholder
| Selection
| File_selector_button
| Moz_focusring
| Webkit_any
| Webkit_autofill
| Moz_placeholder
| Webkit_input_placeholder
| Ms_input_placeholder
| Moz_ui_invalid
| Moz_ui_valid
| Webkit_scrollbar
| Webkit_search_cancel_button
| Webkit_search_decoration
| Webkit_datetime_edit_fields_wrapper
| Webkit_date_and_time_value
| Webkit_datetime_edit
| Webkit_datetime_edit_year_field
| Webkit_datetime_edit_month_field
| Webkit_datetime_edit_day_field
| Webkit_datetime_edit_hour_field
| Webkit_datetime_edit_minute_field
| Webkit_datetime_edit_second_field
| Webkit_datetime_edit_millisecond_field
| Webkit_datetime_edit_meridiem_field
| Webkit_inner_spin_button
| Webkit_outer_spin_button
| Webkit_calendar_picker_indicator
| Is of t list
| Where of t list
| Not of t list
| Has of t list
| Nth_child of nth * t list option
| Nth_last_child of nth * t list option
| Nth_of_type of nth * t list option
| Nth_last_of_type of nth * t list option
| Dir of string
| Lang of string list
| Host of t list option
| Host_context of t list
| State of string
| Active_view_transition_type of string list option
| Heading
| Part of string list
| Slotted of t list
| Cue of t list
| Cue_region of t list
| Highlight of string list
| View_transition_group of string
| View_transition_image_pair of string
| View_transition_old of string
| View_transition_new of string
| Compound of t list
| Combined of t * combinator * t
| List of t list
| Nesting

val element : ?ns:ns -> string -> t

element ?ns name element selector (e.g., "div"). Validates CSS identifiers; raises Invalid_argument on invalid.

val class_ : string -> t

class_ name class selector from raw (unescaped) string. Accepts any serializable characters including special chars that will be escaped during pretty-printing. Only rejects control characters and '--' prefix. Raises Invalid_argument on invalid.

val id : string -> t

id name ID selector from raw (unescaped) string. Accepts any serializable characters including special chars that will be escaped during pretty-printing. Only rejects control characters and '--' prefix. Raises Invalid_argument on invalid.

val of_string : string -> t

of_string s parses a CSS-escaped selector string:

".classname" → class selector
"#idname" → id selector
"element" → element selector

Unescapes both simple escapes (e.g., "\:") and hex escapes (e.g., "\3A"). Example: of_string ".sm\\:p-4" creates a class selector for "sm:p-4".

val universal : t

universal universal selector "*" (no namespace).

val attribute : ?ns:ns -> ?flag:attr_flag -> string -> attribute_match -> t

attribute ?ns ?flag name match attribute selector. Validates identifiers; raises Invalid_argument on invalid.

val combine : t -> combinator -> t -> t

combine a comb b combines selectors with a combinator.

val (++) : t -> t -> t

a ++ b combines with descendant (space).

val (>>) : t -> t -> t

a >> b combines with child (>).

val where : t list -> t

where selectors :where(...) pseudo-class.

val not : t list -> t

not selectors :not(...) pseudo-class.

val list : t list -> t

list selectors comma-separated selector list.

val is_compound_list : t -> bool

is_compound_list selector returns true if already a list of selectors.

val as_list : t -> t list option

as_list selector returns Some selectors if selector is a list, None otherwise. Useful for pattern matching on merged selectors.

val compound : t list -> t

compound selectors compound selector (concatenates simple selectors).

val (&&) : t -> t -> t

a && b combines two simple selectors into a compound selector.

val (||) : t -> t -> t

a || b combines with column combinator (||).

val pp : t Pp.t

pp pretty-prints selectors.

val to_string : ?minify:bool -> t -> string

to_string ?minify sel renders a selector to a string.

val map : (t -> t) -> t -> t

map f selector recursively applies f to all selectors in the tree. The function f is applied bottom-up: first to descendants, then to the current node. This is useful for transforming class names throughout a complex selector structure.

val pp_combinator : combinator Pp.t

pp_combinator pretty-prints selector combinators.

val pp_attribute_match : attribute_match Pp.t

pp_attribute_match pretty-prints attribute matchers.

val pp_ns : ns Pp.t

pp_ns pretty-prints namespaces.

val pp_attr_flag : attr_flag option Pp.t

pp_attr_flag pretty-prints optional attribute flags.

val attr_value_needs_quoting : string -> bool

attr_value_needs_quoting value returns true if the given attribute value requires quoting according to CSS specifications. Values need quotes if:

They are empty
They start with a digit
They start with double hyphen (--)
They contain characters that are not valid in CSS identifiers (anything other than letters, digits, hyphens, underscores, or non-ASCII)

val pp_nth : nth Pp.t

pp_nth pretty-prints nth expressions.

val read_selector_list : Reader.t -> t

read_selector_list r reads a selector list without checking for end of input. Used when parsing selectors as part of a larger CSS structure.

val read : Reader.t -> t

read r parses a CSS selector.

val read_combinator : Reader.t -> combinator

read_combinator r parses a combinator.

val read_attribute_match : Reader.t -> attribute_match

read_attribute_match r parses an attribute matcher.

val read_ns : Reader.t -> ns option

read_ns r parses an optional attribute/selector namespace.

val read_attr_flag : Reader.t -> attr_flag option

read_attr_flag r parses an attribute selector flag (i or s).

val read_nth : Reader.t -> nth

read_nth r parses an An+B nth expression.

val is_ : t list -> t

is_ selectors :is(...) pseudo-class.

val has : t list -> t

has selectors :has(...) pseudo-class.

val nth_child : ?of_:t list -> nth -> t

nth_child ?of_ nth builds :nth-child with optional :of.

val host : ?selectors:t list -> unit -> t

host ?selectors () :host or :host(selector) pseudo-class.

val any : (t -> bool) -> t -> bool

any predicate selector returns true if any node in selector satisfies predicate. Analysis helper (structure-based, no string scanning).

val has_focus : t -> bool

has_focus sel checks presence of :focus pseudo-class in the selector.

val has_focus_within : t -> bool

has_focus_within sel checks presence of :focus-within pseudo-class in the selector.

val has_focus_visible : t -> bool

has_focus_visible sel checks presence of :focus-visible pseudo-class in the selector.

val exists_class : (string -> bool) -> t -> bool

exists_class pred sel returns true if any class node satisfies pred.

val first_class : t -> string option

first_class sel returns the first class name found along the leftmost path (Compound > Class, then left side of Combined, or first in List), or None if no class is found.

val contains_modifier_colon : t -> bool

contains_modifier_colon sel returns true if any class name contains a modifier colon (e.g., "md:...", "hover:...").

val has_group_marker : t -> bool

has_group_marker sel returns true if selector contains :where(.group), indicating a group-* modifier like group-hover, group-focus, group-has.

val has_peer_marker : t -> bool

has_peer_marker sel returns true if selector contains :where(.peer), indicating a peer-* modifier like peer-checked, peer-focus, peer-has.

val has_pseudo_element : t -> bool

has_pseudo_element sel returns true if selector contains a pseudo-element like ::before, ::after, ::marker, etc.

val modifier_prefix : t -> string option

modifier_prefix sel extracts the modifier prefix from the first class in the selector. Returns Some "before:" for ".before:absolute", Some "hover:" for ".hover:bg-blue-500", None for ".shadow" or ".shadow-sm".

This is used by the CSS optimizer to determine if selectors can be safely merged while preserving cascade semantics. Selectors with different modifier prefixes target different elements and must remain separate.