#1: Add Visitor transformation support

Cargo.toml

@@ -11,4 +11,4 @@ crate-type = ["cdylib"]
 [dependencies]
 pyo3 = { version = "0.28.2", features = ["extension-module"] }
 browserslist-rs = "0.19.0"
-lightningcss = { version = "1.0.0-alpha.71", features = ["browserslist"] }
+lightningcss = { version = "1.0.0-alpha.71", features = ["browserslist", "visitor"] }

lightningcss.pyi

@@ -2,19 +2,185 @@
 A python wrapper for the core CSS transformation functionality of lightningcss.
 """
 
+from __future__ import annotations
+
 from typing import NewType
 
 ParserFlags = NewType('ParserFlags', int)
 
+
+class Angle:
+    value: float
+    unit: str
+    def __init__(self, value: float, unit: str) -> None: ...
+
+
+class Ratio:
+    numerator: float
+    denominator: float
+    def __init__(self, numerator: float, denominator: float) -> None: ...
+
+
+class Resolution:
+    value: float
+    unit: str
+    def __init__(self, value: float, unit: str) -> None: ...
+
+
+class Time:
+    value: float
+    unit: str
+    def __init__(self, value: float, unit: str) -> None: ...
+
+
+class LengthValue:
+    value: float
+    unit: str
+    def __init__(self, value: float, unit: str) -> None: ...
+
+
+class CssColor:
+    def __init__(self, css: str) -> None: ...
+    def css(self) -> str: ...
+
+
+class Url:
+    url: str
+    def __init__(self, url: str) -> None: ...
+
+
+class CustomIdent:
+    ident: str
+    def __init__(self, ident: str) -> None: ...
+
+
+class DashedIdent:
+    ident: str
+    def __init__(self, ident: str) -> None: ...
+
+
+class Function:
+    name: str
+    arguments: str
+    def __init__(self, name: str, arguments: str) -> None: ...
+
+
+class Variable:
+    name: str
+    fallback: str | None
+    def __init__(self, name: str, fallback: str | None = None) -> None: ...
+
+
+class EnvironmentVariable:
+    name: str
+    indices: list[int]
+    fallback: str | None
+    def __init__(
+        self,
+        name: str,
+        indices: list[int] = [],
+        fallback: str | None = None,
+    ) -> None: ...
+
+
+class Image:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class Selector:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class MediaQuery:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class SupportsCondition:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class CssRule:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class Property:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class TokenOrValue:
+    css: str
+    def __init__(self, css: str) -> None: ...
+
+
+class Visitor:
+    """
+    Base class for visitors. To create a visitor, subclass this and override
+    the visit methods for the node types you want to observe or mutate. Then,
+    pass an instance of your visitor to `process_stylesheet()` or
+    `bundle_css()`. The visitor will be called for each visited node in the
+    stylesheet, allowing for observation or mutation of the node.
+    """
+    def __init__(self, visit_types: int = 0) -> None: ...
+
+    def visit_url(self, value: Url) -> Url | None: ...
+    def visit_color(self, value: CssColor) -> CssColor | None: ...
+    def visit_length(self, value: LengthValue) -> LengthValue | None: ...
+    def visit_angle(self, value: Angle) -> Angle | None: ...
+    def visit_ratio(self, value: Ratio) -> Ratio | None: ...
+    def visit_resolution(self, value: Resolution) -> Resolution | None: ...
+    def visit_time(self, value: Time) -> Time | None: ...
+    def visit_custom_ident(self, value: CustomIdent) -> CustomIdent | None: ...
+    def visit_dashed_ident(self, value: DashedIdent) -> DashedIdent | None: ...
+
+    def visit_selector(self, value: Selector) -> object | None: ...
+    def visit_rule(self, value: CssRule) -> object | None: ...
+    def visit_property(self, value: Property) -> object | None: ...
+    def visit_image(self, value: Image) -> object | None: ...
+    def visit_variable(self, value: Variable) -> object | None: ...
+    def visit_environment_variable(self, value: EnvironmentVariable) -> object | None: ...
+    def visit_media_query(self, value: MediaQuery) -> object | None: ...
+    def visit_supports_condition(self, value: SupportsCondition) -> object | None: ...
+    def visit_function(self, value: Function) -> object | None: ...
+    def visit_token(self, value: TokenOrValue) -> object | None: ...
+
+
+VISIT_RULES: int
+VISIT_PROPERTIES: int
+VISIT_URLS: int
+VISIT_COLORS: int
+VISIT_IMAGES: int
+VISIT_LENGTHS: int
+VISIT_ANGLES: int
+VISIT_RATIOS: int
+VISIT_RESOLUTIONS: int
+VISIT_TIMES: int
+VISIT_CUSTOM_IDENTS: int
+VISIT_DASHED_IDENTS: int
+VISIT_VARIABLES: int
+VISIT_ENVIRONMENT_VARIABLES: int
+VISIT_MEDIA_QUERIES: int
+VISIT_SUPPORTS_CONDITIONS: int
+VISIT_SELECTORS: int
+VISIT_FUNCTIONS: int
+VISIT_TOKENS: int
+
+
 def calc_parser_flags(
     nesting: bool = False,
     custom_media: bool = False,
-    deep_selector_combinator: bool = False
+    deep_selector_combinator: bool = False,
 ) -> ParserFlags:
     """
     Calculates the `parser_flags` argument of `process_stylesheet()` and `bundle_css()`.
     """
 
+
 def process_stylesheet(
     code: str,
     /,
@@ -23,7 +189,8 @@ def process_stylesheet(
     parser_flags: ParserFlags = ParserFlags(0),
     unused_symbols: set[str] | None = None,
     browsers_list: list[str] | None = None,
-    minify: bool = True
+    minify: bool = True,
+    visitor: Visitor | None = None,
 ) -> str:
     """
     Processes the supplied CSS stylesheet and returns as a string.
@@ -44,17 +211,23 @@ def process_stylesheet(
         specified, no prefixing/transpilation will occur.
     :param minify: If True, the final output will be minified. Otherwise, it
         will be pretty-printed.
+    :param visitor: An optional Visitor instance. If provided, the visitor will
+        be called for each visited node in the stylesheet, allowing for
+        observation or mutation of the node. See the Visitor class for more
+        details.
     :return: A string containing a processed CSS stylesheet.
     """
 
+
 def bundle_css(
     path: str,
     /,
     error_recovery: bool = False,
     parser_flags: ParserFlags = ParserFlags(0),
     unused_symbols: set[str] | None = None,
     browsers_list: list[str] | None = None,
-    minify: bool = True
+    minify: bool = True,
+    visitor: Visitor | None = None,
 ) -> str:
     """
     Processes the supplied CSS stylesheet file and returns the bundle as a string.
@@ -77,5 +250,9 @@ def bundle_css(
         specified, no prefixing/transpilation will occur.
     :param minify: If True, the final output will be minified. Otherwise, it
         will be pretty-printed.
+    :param visitor: An optional Visitor instance. If provided, the visitor will
+        be called for each visited node in the stylesheet, allowing for
+        observation or mutation of the node. See the Visitor class for more
+        details.
     :return: A string containing the CSS bundle.
     """

src/lib.rs

@@ -10,6 +10,9 @@ use lightningcss::stylesheet::{
     MinifyOptions, ParserFlags, ParserOptions, PrinterOptions, StyleSheet,
 };
 use lightningcss::targets::{Browsers, Targets};
+use lightningcss::visitor::{Visit, VisitTypes};
+
+mod visitor;
 
 /// Processes provided CSS and returns as a string.
 ///
@@ -38,14 +41,16 @@ use lightningcss::targets::{Browsers, Targets};
     unused_symbols=None,
     browsers_list=None,
     minify=true,
+    visitor=None,
 ))]
 fn process_stylesheet(code: &str,
                       filename: &str,
                       error_recovery: bool,
                       parser_flags: u8,
                       unused_symbols: Option<HashSet<String>>,
                       browsers_list: Option<Vec<String>>,
-                      minify: bool) -> PyResult<String> {
+                      minify: bool,
+                      visitor: Option<&mut visitor::PyVisitor>) -> PyResult<String> {
 
     let targets = match mk_targets(browsers_list) {
         Ok(val) => val,
@@ -55,6 +60,12 @@ fn process_stylesheet(code: &str,
         Ok(val) => val,
         Err(e) => {return Err(PyValueError::new_err(format!("Parsing stylesheet failed: {}", e.to_string())))}
     };
+    if let Some(visitor) = visitor {
+        match stylesheet.visit(visitor) {
+            Ok(_) => {}
+            Err(e) => {return Err(PyValueError::new_err(format!("Visiting stylesheet failed: {}", e.to_string())))}
+        }
+    };
     match stylesheet.minify(mk_minify_options(unused_symbols, &targets)) {
         Ok(_) => {}
         Err(e) => {return Err(PyValueError::new_err(format!("Minifying stylesheet failed: {}", e.to_string())));}
@@ -123,6 +134,7 @@ fn mk_printer_options<'a>(targets: &Targets,
     unused_symbols=None,
     browsers_list=None,
     minify=true,
+    visitor=None,
 ))]
 fn bundle_css(
     path: &str,
@@ -131,6 +143,7 @@ fn bundle_css(
     unused_symbols: Option<HashSet<String>>,
     browsers_list: Option<Vec<String>>,
     minify: bool,
+    visitor: Option<&mut visitor::PyVisitor>
 ) -> PyResult<String> {
     let fs = FileProvider::new();
     let mut bundler = Bundler::new(
@@ -160,6 +173,13 @@ fn bundle_css(
         }
     };
 
+    if let Some(visitor) = visitor {
+        match stylesheet.visit(visitor) {
+            Ok(_) => {}
+            Err(e) => {return Err(PyValueError::new_err(format!("Visiting stylesheet failed: {}", e.to_string())))}
+        }
+    };
+
     let targets = match mk_targets(browsers_list) {
         Ok(val) => val,
         Err(e) => {
@@ -197,4 +217,87 @@ mod py_lightningcss {
     use super::process_stylesheet;
     #[pymodule_export]
     use super::bundle_css;
+
+    #[pymodule_export(name = "Visitor")]
+    use super::visitor::PyVisitor;
+
+    // Export CSS value type classes
+    #[pymodule_export(name = "Url")]
+    use super::visitor::PyUrl;
+    #[pymodule_export(name = "CssColor")]
+    use super::visitor::PyCssColor;
+    #[pymodule_export(name = "LengthValue")]
+    use super::visitor::PyLengthValue;
+    #[pymodule_export(name = "Angle")]
+    use super::visitor::PyAngle;
+    #[pymodule_export(name = "Ratio")]
+    use super::visitor::PyRatio;
+    #[pymodule_export(name = "Resolution")]
+    use super::visitor::PyResolution;
+    #[pymodule_export(name = "Time")]
+    use super::visitor::PyTime;
+    #[pymodule_export(name = "CustomIdent")]
+    use super::visitor::PyCustomIdent;
+    #[pymodule_export(name = "DashedIdent")]
+    use super::visitor::PyDashedIdent;
+    #[pymodule_export(name = "Selector")]
+    use super::visitor::PySelector;
+    #[pymodule_export(name = "CssRule")]
+    use super::visitor::PyCssRule;
+    #[pymodule_export(name = "Property")]
+    use super::visitor::PyProperty;
+    #[pymodule_export(name = "Image")]
+    use super::visitor::PyImage;
+    #[pymodule_export(name = "Variable")]
+    use super::visitor::PyVariable;
+    #[pymodule_export(name = "EnvironmentVariable")]
+    use super::visitor::PyEnvironmentVariable;
+    #[pymodule_export(name = "MediaQuery")]
+    use super::visitor::PyMediaQuery;
+    #[pymodule_export(name = "SupportsCondition")]
+    use super::visitor::PySupportsCondition;
+    #[pymodule_export(name = "Function")]
+    use super::visitor::PyFunction;
+    #[pymodule_export(name = "TokenOrValue")]
+    use super::visitor::PyTokenOrValue;
+
+    // Export all VisitTypes flag constants so they're accessible from Python
+    #[pymodule_export]
+    const VISIT_RULES: u32 = super::VisitTypes::RULES.bits();
+    #[pymodule_export]
+    const VISIT_PROPERTIES: u32 = super::VisitTypes::PROPERTIES.bits();
+    #[pymodule_export]
+    const VISIT_URLS: u32 = super::VisitTypes::URLS.bits();
+    #[pymodule_export]
+    const VISIT_COLORS: u32 = super::VisitTypes::COLORS.bits();
+    #[pymodule_export]
+    const VISIT_IMAGES: u32 = super::VisitTypes::IMAGES.bits();
+    #[pymodule_export]
+    const VISIT_LENGTHS: u32 = super::VisitTypes::LENGTHS.bits();
+    #[pymodule_export]
+    const VISIT_ANGLES: u32 = super::VisitTypes::ANGLES.bits();
+    #[pymodule_export]
+    const VISIT_RATIOS: u32 = super::VisitTypes::RATIOS.bits();
+    #[pymodule_export]
+    const VISIT_RESOLUTIONS: u32 = super::VisitTypes::RESOLUTIONS.bits();
+    #[pymodule_export]
+    const VISIT_TIMES: u32 = super::VisitTypes::TIMES.bits();
+    #[pymodule_export]
+    const VISIT_CUSTOM_IDENTS: u32 = super::VisitTypes::CUSTOM_IDENTS.bits();
+    #[pymodule_export]
+    const VISIT_DASHED_IDENTS: u32 = super::VisitTypes::DASHED_IDENTS.bits();
+    #[pymodule_export]
+    const VISIT_VARIABLES: u32 = super::VisitTypes::VARIABLES.bits();
+    #[pymodule_export]
+    const VISIT_ENVIRONMENT_VARIABLES: u32 = super::VisitTypes::ENVIRONMENT_VARIABLES.bits();
+    #[pymodule_export]
+    const VISIT_MEDIA_QUERIES: u32 = super::VisitTypes::MEDIA_QUERIES.bits();
+    #[pymodule_export]
+    const VISIT_SUPPORTS_CONDITIONS: u32 = super::VisitTypes::SUPPORTS_CONDITIONS.bits();
+    #[pymodule_export]
+    const VISIT_SELECTORS: u32 = super::VisitTypes::SELECTORS.bits();
+    #[pymodule_export]
+    const VISIT_FUNCTIONS: u32 = super::VisitTypes::FUNCTIONS.bits();
+    #[pymodule_export]
+    const VISIT_TOKENS: u32 = super::VisitTypes::TOKENS.bits();
 }