Xteink-X4-crosspoint-reader/lib/Epub/Epub/css/CssParser.h
Jake Kenneally f0ac68d26c Address review comments
- Renamed `getIndentWidth` to `getTextAdvanceX`
- Collapsed `Style` and `BlockStyle` into a single struct, and switched to using bitflag setup for determining font style in `EpdFontFamily::Style`, including underlined text
- Added caching for parsed CSS rules
- Reverted changes for fixing spurious spaces
- Skipped loading CSS on Sleep and HomeScreen activities, since we only need BookMetadata and the cover image
- Reverted changes to BookMetadataCache, since we don't need to cache the individual CSS files and can instead use the parsed CSS rules (and the new cache file for those)
- Switched intermediary values to direct assignment in `CssParser.cpp`
- Added function in `BlockStyle.h` to directly convert from a `CssStyle` to a `BlockStyle`, as well as combined multiple `BlockStyle`s together for nested elements that should inherit the parent's style when the child's is unspecified
- Updated names of variables in `CssStyle` to match those of the CSS they represent (e.g. alignment -> textAlign, indent -> textIndent)
- General cleaning up and simplifying the code
2026-02-02 22:18:06 -05:00

115 lines
3.6 KiB
C++

#pragma once
#include <SdFat.h>
#include <string>
#include <unordered_map>
#include <vector>
#include "CssStyle.h"
/**
* Lightweight CSS parser for EPUB stylesheets
*
* Parses CSS files and extracts styling information relevant for e-ink display.
* Uses a two-phase approach: first tokenizes the CSS content, then builds
* a rule database that can be queried during HTML parsing.
*
* Supported selectors:
* - Element selectors: p, div, h1, etc.
* - Class selectors: .classname
* - Combined: element.classname
* - Grouped: selector1, selector2 { }
*
* Not supported (silently ignored):
* - Descendant/child selectors
* - Pseudo-classes and pseudo-elements
* - Media queries (content is skipped)
* - @import, @font-face, etc.
*/
class CssParser {
public:
CssParser() = default;
~CssParser() = default;
// Non-copyable
CssParser(const CssParser&) = delete;
CssParser& operator=(const CssParser&) = delete;
/**
* Load and parse CSS from a file stream.
* Can be called multiple times to accumulate rules from multiple stylesheets.
* @param source Open file handle to read from
* @return true if parsing completed (even if no rules found)
*/
bool loadFromStream(FsFile& source);
/**
* Look up the style for an HTML element, considering tag name and class attributes.
* Applies CSS cascade: element style < class style < element.class style
*
* @param tagName The HTML element name (e.g., "p", "div")
* @param classAttr The class attribute value (may contain multiple space-separated classes)
* @return Combined style with all applicable rules merged
*/
[[nodiscard]] CssStyle resolveStyle(const std::string& tagName, const std::string& classAttr) const;
/**
* Parse an inline style attribute string.
* @param styleValue The value of a style="" attribute
* @return Parsed style properties
*/
[[nodiscard]] static CssStyle parseInlineStyle(const std::string& styleValue);
/**
* Check if any rules have been loaded
*/
[[nodiscard]] bool empty() const { return rulesBySelector_.empty(); }
/**
* Get count of loaded rule sets
*/
[[nodiscard]] size_t ruleCount() const { return rulesBySelector_.size(); }
/**
* Clear all loaded rules
*/
void clear() { rulesBySelector_.clear(); }
/**
* Save parsed CSS rules to a cache file.
* @param file Open file handle to write to
* @return true if cache was written successfully
*/
bool saveToCache(FsFile& file) const;
/**
* Load CSS rules from a cache file.
* Clears any existing rules before loading.
* @param file Open file handle to read from
* @return true if cache was loaded successfully
*/
bool loadFromCache(FsFile& file);
private:
// Storage: maps normalized selector -> style properties
std::unordered_map<std::string, CssStyle> rulesBySelector_;
// Internal parsing helpers
void processRuleBlock(const std::string& selectorGroup, const std::string& declarations);
static CssStyle parseDeclarations(const std::string& declBlock);
// Individual property value parsers
static CssTextAlign interpretAlignment(const std::string& val);
static CssFontStyle interpretFontStyle(const std::string& val);
static CssFontWeight interpretFontWeight(const std::string& val);
static CssTextDecoration interpretDecoration(const std::string& val);
static CssLength interpretLength(const std::string& val);
static int8_t interpretSpacing(const std::string& val);
// String utilities
static std::string normalized(const std::string& s);
static std::vector<std::string> splitOnChar(const std::string& s, char delimiter);
static std::vector<std::string> splitWhitespace(const std::string& s);
};