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Diffstat (limited to 'devtools/shared/css/parsing-utils.js')
| -rw-r--r-- | devtools/shared/css/parsing-utils.js | 736 |
1 files changed, 736 insertions, 0 deletions
diff --git a/devtools/shared/css/parsing-utils.js b/devtools/shared/css/parsing-utils.js new file mode 100644 index 0000000000..8ef8ce41ba --- /dev/null +++ b/devtools/shared/css/parsing-utils.js @@ -0,0 +1,736 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +// This file holds various CSS parsing and rewriting utilities. +// Some entry points of note are: +// parseDeclarations - parse a CSS rule into declarations +// parsePseudoClassesAndAttributes - parse selector and extract +// pseudo-classes +// parseSingleValue - parse a single CSS property value + +"use strict"; + +const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js"); + +loader.lazyRequireGetter( + this, + "CSS_ANGLEUNIT", + "resource://devtools/shared/css/constants.js", + true +); + +const SELECTOR_ATTRIBUTE = (exports.SELECTOR_ATTRIBUTE = 1); +const SELECTOR_ELEMENT = (exports.SELECTOR_ELEMENT = 2); +const SELECTOR_PSEUDO_CLASS = (exports.SELECTOR_PSEUDO_CLASS = 3); +const CSS_BLOCKS = { "(": ")", "[": "]", "{": "}" }; + +// When commenting out a declaration, we put this character into the +// comment opener so that future parses of the commented text know to +// bypass the property name validity heuristic. +const COMMENT_PARSING_HEURISTIC_BYPASS_CHAR = + (exports.COMMENT_PARSING_HEURISTIC_BYPASS_CHAR = "!"); + +/** + * A generator function that lexes a CSS source string, yielding the + * CSS tokens. Comment tokens are dropped. + * + * @param {String} CSS source string + * @yield {CSSToken} The next CSSToken that is lexed + * @see CSSToken for details about the returned tokens + */ +function* cssTokenizer(string) { + const lexer = getCSSLexer(string); + while (true) { + const token = lexer.nextToken(); + if (!token) { + break; + } + // None of the existing consumers want comments. + if (token.tokenType !== "comment") { + yield token; + } + } +} + +/** + * Pass |string| to the CSS lexer and return an array of all the + * returned tokens. Comment tokens are not included. In addition to + * the usual information, each token will have starting and ending + * line and column information attached. Specifically, each token + * has an additional "loc" attribute. This attribute is an object + * of the form {line: L, column: C}. Lines and columns are both zero + * based. + * + * It's best not to add new uses of this function. In general it is + * simpler and better to use the CSSToken offsets, rather than line + * and column. Also, this function lexes the entire input string at + * once, rather than lazily yielding a token stream. Use + * |cssTokenizer| or |getCSSLexer| instead. + * + * @param{String} string The input string. + * @return {Array} An array of tokens (@see CSSToken) that have + * line and column information. + */ +function cssTokenizerWithLineColumn(string) { + const lexer = getCSSLexer(string); + const result = []; + let prevToken = undefined; + while (true) { + const token = lexer.nextToken(); + const lineNumber = lexer.lineNumber; + const columnNumber = lexer.columnNumber; + + if (prevToken) { + prevToken.loc.end = { + line: lineNumber, + column: columnNumber, + }; + } + + if (!token) { + break; + } + + if (token.tokenType === "comment") { + // We've already dealt with the previous token's location. + prevToken = undefined; + } else { + const startLoc = { + line: lineNumber, + column: columnNumber, + }; + token.loc = { start: startLoc }; + + result.push(token); + prevToken = token; + } + } + + return result; +} + +/** + * Escape a comment body. Find the comment start and end strings in a + * string and inserts backslashes so that the resulting text can + * itself be put inside a comment. + * + * @param {String} inputString + * input string + * @return {String} the escaped result + */ +function escapeCSSComment(inputString) { + const result = inputString.replace(/\/(\\*)\*/g, "/\\$1*"); + return result.replace(/\*(\\*)\//g, "*\\$1/"); +} + +/** + * Un-escape a comment body. This undoes any comment escaping that + * was done by escapeCSSComment. That is, given input like "/\* + * comment *\/", it will strip the backslashes. + * + * @param {String} inputString + * input string + * @return {String} the un-escaped result + */ +function unescapeCSSComment(inputString) { + const result = inputString.replace(/\/\\(\\*)\*/g, "/$1*"); + return result.replace(/\*\\(\\*)\//g, "*$1/"); +} + +/** + * A helper function for @see parseDeclarations that handles parsing + * of comment text. This wraps a recursive call to parseDeclarations + * with the processing needed to ensure that offsets in the result + * refer back to the original, unescaped, input string. + * + * @param {Function} isCssPropertyKnown + * A function to check if the CSS property is known. This is either an + * internal server function or from the CssPropertiesFront. + * @param {String} commentText The text of the comment, without the + * delimiters. + * @param {Number} startOffset The offset of the comment opener + * in the original text. + * @param {Number} endOffset The offset of the comment closer + * in the original text. + * @return {array} Array of declarations of the same form as returned + * by parseDeclarations. + */ +function parseCommentDeclarations( + isCssPropertyKnown, + commentText, + startOffset, + endOffset +) { + let commentOverride = false; + if (commentText === "") { + return []; + } else if (commentText[0] === COMMENT_PARSING_HEURISTIC_BYPASS_CHAR) { + // This is the special sign that the comment was written by + // rewriteDeclarations and so we should bypass the usual + // heuristic. + commentOverride = true; + commentText = commentText.substring(1); + } + + const rewrittenText = unescapeCSSComment(commentText); + + // We might have rewritten an embedded comment. For example + // /\* ... *\/ would turn into /* ... */. + // This rewriting is necessary for proper lexing, but it means + // that the offsets we get back can be off. So now we compute + // a map so that we can rewrite offsets later. The map is the same + // length as |rewrittenText| and tells us how to map an index + // into |rewrittenText| to an index into |commentText|. + // + // First, we find the location of each comment starter or closer in + // |rewrittenText|. At these spots we put a 1 into |rewrites|. + // Then we walk the array again, using the elements to compute a + // delta, which we use to make the final mapping. + // + // Note we allocate one extra entry because we can see an ending + // offset that is equal to the length. + const rewrites = new Array(rewrittenText.length + 1).fill(0); + + const commentRe = /\/\\*\*|\*\\*\//g; + while (true) { + const matchData = commentRe.exec(rewrittenText); + if (!matchData) { + break; + } + rewrites[matchData.index] = 1; + } + + let delta = 0; + for (let i = 0; i <= rewrittenText.length; ++i) { + delta += rewrites[i]; + // |startOffset| to add the offset from the comment starter, |+2| + // for the length of the "/*", then |i| and |delta| as described + // above. + rewrites[i] = startOffset + 2 + i + delta; + if (commentOverride) { + ++rewrites[i]; + } + } + + // Note that we pass "false" for parseComments here. It doesn't + // seem worthwhile to support declarations in comments-in-comments + // here, as there's no way to generate those using the tools, and + // users would be crazy to write such things. + const newDecls = parseDeclarationsInternal( + isCssPropertyKnown, + rewrittenText, + false, + true, + commentOverride + ); + for (const decl of newDecls) { + decl.offsets[0] = rewrites[decl.offsets[0]]; + decl.offsets[1] = rewrites[decl.offsets[1]]; + decl.colonOffsets[0] = rewrites[decl.colonOffsets[0]]; + decl.colonOffsets[1] = rewrites[decl.colonOffsets[1]]; + decl.commentOffsets = [startOffset, endOffset]; + } + return newDecls; +} + +/** + * A helper function for parseDeclarationsInternal that creates a new + * empty declaration. + * + * @return {object} an empty declaration of the form returned by + * parseDeclarations + */ +function getEmptyDeclaration() { + return { + name: "", + value: "", + priority: "", + terminator: "", + offsets: [undefined, undefined], + colonOffsets: false, + }; +} + +/** + * Like trim, but only trims CSS-allowed whitespace. + */ +function cssTrim(str) { + const match = /^[ \t\r\n\f]*(.*?)[ \t\r\n\f]*$/.exec(str); + if (match) { + return match[1]; + } + return str; +} + +/** + * A helper function that does all the parsing work for + * parseDeclarations. This is separate because it has some arguments + * that don't make sense in isolation. + * + * The return value and arguments are like parseDeclarations, with + * these additional arguments. + * + * @param {Function} isCssPropertyKnown + * Function to check if the CSS property is known. + * @param {Boolean} inComment + * If true, assume that this call is parsing some text + * which came from a comment in another declaration. + * In this case some heuristics are used to avoid parsing + * text which isn't obviously a series of declarations. + * @param {Boolean} commentOverride + * This only makes sense when inComment=true. + * When true, assume that the comment was generated by + * rewriteDeclarations, and skip the usual name-checking + * heuristic. + */ +// eslint-disable-next-line complexity +function parseDeclarationsInternal( + isCssPropertyKnown, + inputString, + parseComments, + inComment, + commentOverride +) { + if (inputString === null || inputString === undefined) { + throw new Error("empty input string"); + } + + const lexer = getCSSLexer(inputString); + + let declarations = [getEmptyDeclaration()]; + let lastProp = declarations[0]; + + // This tracks the various CSS blocks the current token is in currently. + // This is a stack we push to when a block is opened, and we pop from when a block is + // closed. Within a block, colons and semicolons don't advance the way they do outside + // of blocks. + let currentBlocks = []; + + // This tracks the "!important" parsing state. The states are: + // 0 - haven't seen anything + // 1 - have seen "!", looking for "important" next (possibly after + // whitespace). + // 2 - have seen "!important" + let importantState = 0; + // This is true if we saw whitespace or comments between the "!" and + // the "important". + let importantWS = false; + let current = ""; + while (true) { + const token = lexer.nextToken(); + if (!token) { + break; + } + + // Update the start and end offsets of the declaration, but only + // when we see a significant token. + if (token.tokenType !== "whitespace" && token.tokenType !== "comment") { + if (lastProp.offsets[0] === undefined) { + lastProp.offsets[0] = token.startOffset; + } + lastProp.offsets[1] = token.endOffset; + } else if ( + lastProp.name && + !current && + !importantState && + !lastProp.priority && + lastProp.colonOffsets[1] + ) { + // Whitespace appearing after the ":" is attributed to it. + lastProp.colonOffsets[1] = token.endOffset; + } else if (importantState === 1) { + importantWS = true; + } + + if ( + token.tokenType === "symbol" && + currentBlocks[currentBlocks.length - 1] === token.text + ) { + // Closing the last block that was opened. + currentBlocks.pop(); + current += token.text; + } else if (token.tokenType === "symbol" && CSS_BLOCKS[token.text]) { + // Opening a new block. + currentBlocks.push(CSS_BLOCKS[token.text]); + current += token.text; + } else if (token.tokenType === "function") { + // Opening a function is like opening a new block, so push one to the stack. + currentBlocks.push(CSS_BLOCKS["("]); + current += token.text + "("; + } else if (token.tokenType === "symbol" && token.text === ":") { + // Either way, a "!important" we've seen is no longer valid now. + importantState = 0; + importantWS = false; + if (!lastProp.name) { + // Set the current declaration name if there's no name yet + lastProp.name = cssTrim(current); + lastProp.colonOffsets = [token.startOffset, token.endOffset]; + current = ""; + currentBlocks = []; + + // When parsing a comment body, if the left-hand-side is not a + // valid property name, then drop it and stop parsing. + if ( + inComment && + !commentOverride && + !isCssPropertyKnown(lastProp.name) + ) { + lastProp.name = null; + break; + } + } else { + // Otherwise, just append ':' to the current value (declaration value + // with colons) + current += ":"; + } + } else if ( + token.tokenType === "symbol" && + token.text === ";" && + !currentBlocks.length + ) { + lastProp.terminator = ""; + // When parsing a comment, if the name hasn't been set, then we + // have probably just seen an ordinary semicolon used in text, + // so drop this and stop parsing. + if (inComment && !lastProp.name) { + current = ""; + currentBlocks = []; + break; + } + if (importantState === 2) { + lastProp.priority = "important"; + } else if (importantState === 1) { + current += "!"; + if (importantWS) { + current += " "; + } + } + lastProp.value = cssTrim(current); + current = ""; + currentBlocks = []; + importantState = 0; + importantWS = false; + declarations.push(getEmptyDeclaration()); + lastProp = declarations[declarations.length - 1]; + } else if (token.tokenType === "ident") { + if (token.text === "important" && importantState === 1) { + importantState = 2; + } else { + if (importantState > 0) { + current += "!"; + if (importantWS) { + current += " "; + } + if (importantState === 2) { + current += "important "; + } + importantState = 0; + importantWS = false; + } + // Re-escape the token to avoid dequoting problems. + // See bug 1287620. + current += CSS.escape(token.text); + } + } else if (token.tokenType === "symbol" && token.text === "!") { + importantState = 1; + } else if (token.tokenType === "whitespace") { + if (current !== "") { + current = current.trimRight() + " "; + } + } else if (token.tokenType === "comment") { + if (parseComments && !lastProp.name && !lastProp.value) { + const commentText = inputString.substring( + token.startOffset + 2, + token.endOffset - 2 + ); + const newDecls = parseCommentDeclarations( + isCssPropertyKnown, + commentText, + token.startOffset, + token.endOffset + ); + + // Insert the new declarations just before the final element. + const lastDecl = declarations.pop(); + declarations = [...declarations, ...newDecls, lastDecl]; + } else { + current = current.trimRight() + " "; + } + } else { + if (importantState > 0) { + current += "!"; + if (importantWS) { + current += " "; + } + if (importantState === 2) { + current += "important "; + } + importantState = 0; + importantWS = false; + } + current += inputString.substring(token.startOffset, token.endOffset); + } + } + + // Handle whatever trailing properties or values might still be there + if (current) { + if (!lastProp.name) { + // Ignore this case in comments. + if (!inComment) { + // Trailing property found, e.g. p1:v1;p2:v2;p3 + lastProp.name = cssTrim(current); + } + } else { + // Trailing value found, i.e. value without an ending ; + if (importantState === 2) { + lastProp.priority = "important"; + } else if (importantState === 1) { + current += "!"; + } + lastProp.value = cssTrim(current); + const terminator = lexer.performEOFFixup("", true); + lastProp.terminator = terminator + ";"; + // If the input was unterminated, attribute the remainder to + // this property. This avoids some bad behavior when rewriting + // an unterminated comment. + if (terminator) { + lastProp.offsets[1] = inputString.length; + } + } + } + + // Remove declarations that have neither a name nor a value + declarations = declarations.filter(prop => prop.name || prop.value); + + return declarations; +} + +/** + * Returns an array of CSS declarations given a string. + * For example, parseDeclarations(isCssPropertyKnown, "width: 1px; height: 1px") + * would return: + * [{name:"width", value: "1px"}, {name: "height", "value": "1px"}] + * + * The input string is assumed to only contain declarations so { and } + * characters will be treated as part of either the property or value, + * depending where it's found. + * + * @param {Function} isCssPropertyKnown + * A function to check if the CSS property is known. This is either an + * internal server function or from the CssPropertiesFront. + * that are supported by the server. + * @param {String} inputString + * An input string of CSS + * @param {Boolean} parseComments + * If true, try to parse the contents of comments as well. + * A comment will only be parsed if it occurs outside of + * the body of some other declaration. + * @return {Array} an array of objects with the following signature: + * [{"name": string, "value": string, "priority": string, + * "terminator": string, + * "offsets": [start, end], "colonOffsets": [start, end]}, + * ...] + * Here, "offsets" holds the offsets of the start and end + * of the declaration text, in a form suitable for use with + * String.substring. + * "terminator" is a string to use to terminate the declaration, + * usually "" to mean no additional termination is needed. + * "colonOffsets" holds the start and end locations of the + * ":" that separates the property name from the value. + * If the declaration appears in a comment, then there will + * be an additional {"commentOffsets": [start, end] property + * on the object, which will hold the offsets of the start + * and end of the enclosing comment. + */ +function parseDeclarations( + isCssPropertyKnown, + inputString, + parseComments = false +) { + return parseDeclarationsInternal( + isCssPropertyKnown, + inputString, + parseComments, + false, + false + ); +} + +/** + * Like @see parseDeclarations, but removes properties that do not + * have a name. + */ +function parseNamedDeclarations( + isCssPropertyKnown, + inputString, + parseComments = false +) { + return parseDeclarations( + isCssPropertyKnown, + inputString, + parseComments + ).filter(item => !!item.name); +} + +/** + * Returns an array of the parsed CSS selector value and type given a string. + * + * The components making up the CSS selector can be extracted into 3 different + * types: element, attribute and pseudoclass. The object that is appended to + * the returned array contains the value related to one of the 3 types described + * along with the actual type. + * + * The following are the 3 types that can be returned in the object signature: + * (1) SELECTOR_ATTRIBUTE + * (2) SELECTOR_ELEMENT + * (3) SELECTOR_PSEUDO_CLASS + * + * @param {String} value + * The CSS selector text. + * @return {Array} an array of objects with the following signature: + * [{ "value": string, "type": integer }, ...] + */ +// eslint-disable-next-line complexity +function parsePseudoClassesAndAttributes(value) { + if (!value) { + throw new Error("empty input string"); + } + + const tokens = cssTokenizer(value); + const result = []; + let current = ""; + let functionCount = 0; + let hasAttribute = false; + let hasColon = false; + + for (const token of tokens) { + if (token.tokenType === "ident") { + current += value.substring(token.startOffset, token.endOffset); + + if (hasColon && !functionCount) { + if (current) { + result.push({ value: current, type: SELECTOR_PSEUDO_CLASS }); + } + + current = ""; + hasColon = false; + } + } else if (token.tokenType === "symbol" && token.text === ":") { + if (!hasColon) { + if (current) { + result.push({ value: current, type: SELECTOR_ELEMENT }); + } + + current = ""; + hasColon = true; + } + + current += token.text; + } else if (token.tokenType === "function") { + current += value.substring(token.startOffset, token.endOffset); + functionCount++; + } else if (token.tokenType === "symbol" && token.text === ")") { + current += token.text; + + if (hasColon && functionCount == 1) { + if (current) { + result.push({ value: current, type: SELECTOR_PSEUDO_CLASS }); + } + + current = ""; + functionCount--; + hasColon = false; + } else { + functionCount--; + } + } else if (token.tokenType === "symbol" && token.text === "[") { + if (!hasAttribute && !functionCount) { + if (current) { + result.push({ value: current, type: SELECTOR_ELEMENT }); + } + + current = ""; + hasAttribute = true; + } + + current += token.text; + } else if (token.tokenType === "symbol" && token.text === "]") { + current += token.text; + + if (hasAttribute && !functionCount) { + if (current) { + result.push({ value: current, type: SELECTOR_ATTRIBUTE }); + } + + current = ""; + hasAttribute = false; + } + } else { + current += value.substring(token.startOffset, token.endOffset); + } + } + + if (current) { + result.push({ value: current, type: SELECTOR_ELEMENT }); + } + + return result; +} + +/** + * Expects a single CSS value to be passed as the input and parses the value + * and priority. + * + * @param {Function} isCssPropertyKnown + * A function to check if the CSS property is known. This is either an + * internal server function or from the CssPropertiesFront. + * that are supported by the server. + * @param {String} value + * The value from the text editor. + * @return {Object} an object with 'value' and 'priority' properties. + */ +function parseSingleValue(isCssPropertyKnown, value) { + const declaration = parseDeclarations( + isCssPropertyKnown, + "a: " + value + ";" + )[0]; + return { + value: declaration ? declaration.value : "", + priority: declaration ? declaration.priority : "", + }; +} + +/** + * Convert an angle value to degree. + * + * @param {Number} angleValue The angle value. + * @param {CSS_ANGLEUNIT} angleUnit The angleValue's angle unit. + * @return {Number} An angle value in degree. + */ +function getAngleValueInDegrees(angleValue, angleUnit) { + switch (angleUnit) { + case CSS_ANGLEUNIT.deg: + return angleValue; + case CSS_ANGLEUNIT.grad: + return angleValue * 0.9; + case CSS_ANGLEUNIT.rad: + return (angleValue * 180) / Math.PI; + case CSS_ANGLEUNIT.turn: + return angleValue * 360; + default: + throw new Error("No matched angle unit."); + } +} + +exports.cssTokenizer = cssTokenizer; +exports.cssTokenizerWithLineColumn = cssTokenizerWithLineColumn; +exports.escapeCSSComment = escapeCSSComment; +exports.unescapeCSSComment = unescapeCSSComment; +exports.parseDeclarations = parseDeclarations; +exports.parseNamedDeclarations = parseNamedDeclarations; +// parseCommentDeclarations is exported for testing. +exports._parseCommentDeclarations = parseCommentDeclarations; +exports.parsePseudoClassesAndAttributes = parsePseudoClassesAndAttributes; +exports.parseSingleValue = parseSingleValue; +exports.getAngleValueInDegrees = getAngleValueInDegrees; |