org.serversass.Parser Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of server-sass Show documentation
Show all versions of server-sass Show documentation
server-sass is a simple implementation of SASS (sass-lang.org)
/*
* Made with all the love in the world
* by scireum in Remshalden, Germany
*
* Copyright by scireum GmbH
* http://www.scireum.de - [email protected]
*/
package org.serversass;
import org.serversass.ast.*;
import org.serversass.ast.Number;
import parsii.tokenizer.Char;
import parsii.tokenizer.ParseException;
import parsii.tokenizer.Token;
import parsii.tokenizer.Tokenizer;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
/**
* Parses a given SASS source into a {@link Stylesheet}.
*
* @author Andreas Haufler ([email protected])
* @since 2014/02
*/
public class Parser {
/**
* How to put that right: CSS is kind of "special gifted" - so tokenization is not always that straightforward.
*
* Therefore we subclass the tokenizer to handle css selectors etc. right here in the tokenizer.
*
*/
class SassTokenizer extends Tokenizer {
public SassTokenizer(Reader input) {
super(input);
setLineComment("//");
setBlockCommentStart("/*");
setBlockCommentEnd("*/");
addSpecialIdStarter('@');
addSpecialIdStarter('$');
addSpecialIdStarter('#');
addKeyword("import");
addKeyword("mixin");
addKeyword("include");
addKeyword("extend");
addKeyword("media");
addStringDelimiter('\'', '\'');
}
@Override
protected Token fetchNumber() {
Token token = super.fetchNumber();
// If a number is immediately followed by % or a text like "px" - this belongs to the numeric token.
if (input.current().is('%')) {
token.addToContent(input.consume());
return token;
}
while (input.current().isLetter()) {
token.addToContent(input.consume());
}
return token;
}
@Override
protected boolean handleStringEscape(char separator, char escapeChar, Token stringToken) {
// All escaped characters will be kept in original form...
stringToken.addToContent(input.consume());
return true;
}
@Override
protected boolean isAtBracket(boolean inSymbol) {
// Treat % as single symbol so that 10%; is not tokenized to
// "10", "%;" but to "10", "%", ";"
// The title of this method might be a bit misleading
return super.isAtBracket(inSymbol) || input.current().is('%');
}
@Override
protected boolean isAtStartOfIdentifier() {
if (super.isAtStartOfIdentifier()) {
return true;
}
// Support vendor specific and class selectors like -moz-border-radius or .test
if ((input.current().is('-') || input.current().is('.')) && input.next().isLetter()) {
return true;
}
return false;
}
@Override
protected boolean isIdentifierChar(Char current) {
if (super.isIdentifierChar(current)) {
return true;
}
// CSS selectors can contain "-", "." or "#" as long as it is not the last character of the token
if ((current.is('-') || current.is('.') || current.is('#')) && !input.next().isWhitepace()) {
return true;
}
return false;
}
@Override
protected boolean isSymbolCharacter(Char ch) {
return super.isSymbolCharacter(ch) && !ch.is('#');
}
}
private final SassTokenizer tokenizer;
private Stylesheet result;
/**
* Creates a new tokenizer parsing the input with the given name.
*
* @param name name of the file being parsed
* @param input the data to parse
*/
public Parser(String name, Reader input) {
tokenizer = new SassTokenizer(input);
result = new Stylesheet(name);
}
/**
* Parses the given input returning the parsed stylesheet.
*
* @return the AST representation of the parsed input
* @throws ParseException if one or more problems occurred while parsing
*/
public Stylesheet parse() throws ParseException {
while (tokenizer.more()) {
if (tokenizer.current().isKeyword("import")) {
// Handle @import
parseImport();
} else if (tokenizer.current().isKeyword("mixin")) {
// Handle @mixin
Mixin mixin = parseMixin();
if (mixin.getName() != null) {
result.addMixin(mixin);
}
} else if (tokenizer.current().isKeyword("media")) {
// Handle @media
result.addSection(parseSection(true));
} else if (tokenizer.current().isSpecialIdentifier("$") && tokenizer.next().isSymbol(":")) {
// Handle variable definition
parseVariableDeclaration();
} else {
// Everything else is a "normal" section with selectors and attributes
result.addSection(parseSection(false));
}
}
// Something went wrong? Throw an exception
if (!tokenizer.getProblemCollector().isEmpty()) {
throw ParseException.create(tokenizer.getProblemCollector());
}
return result;
}
/**
* Parses a "section" which is either a media query or a css selector along with a set of attributes.
*
* @param mediaQuery determines if we're about to parse a media query or a "normal" section
* @return the parsed section
*/
private Section parseSection(boolean mediaQuery) {
Section result = new Section();
if (mediaQuery) {
// Parse a media query like @media screen and (min-width: 1200px)
tokenizer.consumeExpectedKeyword("media");
while (true) {
if (tokenizer.current().isIdentifier()) {
// Handle plain identifiers like "screen" or "print"
result.addMediaQuery(new Value(tokenizer.consume().getContents()));
} else if (tokenizer.current().isSymbol("(")) {
// Handle filters like (orientation: landscape)
tokenizer.consumeExpectedSymbol("(");
if (tokenizer.current().isIdentifier() && tokenizer.next().isSymbol(":")) {
MediaFilter attr = new MediaFilter(tokenizer.consume().getContents());
tokenizer.consumeExpectedSymbol(":");
attr.setExpression(parseExpression(true));
result.addMediaQuery(attr);
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected symbol: '%s'. Expected an attribute filter.",
tokenizer.current().getSource());
}
tokenizer.consumeExpectedSymbol(")");
} else {
break;
}
// We only handle "and" as conjunction between two filters
if (!tokenizer.current().isIdentifier("and")) {
break;
} else {
tokenizer.consume();
}
}
} else {
// Parse selectors like "b div.test"
while (tokenizer.more()) {
List selector = parseSelector();
result.getSelectors().add(selector);
// If another selector is given, swallow the "," and parse the next selector, else we're done.
if (!tokenizer.current().isSymbol(",")) {
break;
} else {
tokenizer.consumeExpectedSymbol(",");
}
}
}
tokenizer.consumeExpectedSymbol("{");
while (tokenizer.more()) {
if (tokenizer.current().isSymbol("}")) {
tokenizer.consumeExpectedSymbol("}");
return result;
}
// Parse "normal" attributes like "font-weight: bold;"
if (tokenizer.current().isIdentifier() && tokenizer.next().isSymbol(":")) {
Attribute attr = new Attribute(tokenizer.consume().getContents());
tokenizer.consumeExpectedSymbol(":");
attr.setExpression(parseExpression(true));
result.addAttribute(attr);
if (tokenizer.current().isSymbol(";") || !tokenizer.next().isSymbol("}")) {
tokenizer.consumeExpectedSymbol(";");
}
} else if (tokenizer.current().isKeyword("media")) {
// Take care of @media sub sections
result.addSubSection(parseSection(true));
} else if (tokenizer.current().isKeyword("include")) {
// Take care of included mixins like "@include border(15px);"
tokenizer.consumeExpectedKeyword("include");
MixinReference ref = new MixinReference();
if (tokenizer.current().isIdentifier()) {
ref.setName(tokenizer.consume().getContents());
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.current()
.getSource() + "'. Expected a mixin to use"
);
}
if (tokenizer.current().isSymbol("(")) {
tokenizer.consumeExpectedSymbol("(");
// Parse parameters - be as error tolerant as possible
while (tokenizer.more() && !tokenizer.current().isSymbol(")", ";", "{", "}")) {
ref.addParameter(parseExpression(false));
if (tokenizer.current().isSymbol(",")) {
tokenizer.consumeExpectedSymbol(",");
} else if (!tokenizer.current().isSymbol(")")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume()
.getSource() + "'. Expected a comma between the parameters."
);
}
}
tokenizer.consumeExpectedSymbol(")");
}
if (tokenizer.current().isSymbol(";") || !tokenizer.next().isSymbol("}")) {
tokenizer.consumeExpectedSymbol(";");
}
if (ref.getName() != null) {
result.addMixinReference(ref);
}
} else if (tokenizer.current().isKeyword("extend")) {
// Parse @extend instructions like "@extend .warning"
tokenizer.consumeExpectedKeyword("extend");
if (tokenizer.current().isIdentifier() || tokenizer.current().isSpecialIdentifier("#")) {
result.addExtends(tokenizer.consume().getSource());
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.current()
.getSource() + "'. Expected a selector to include."
);
}
if (tokenizer.current().isSymbol(";") || !tokenizer.next().isSymbol("}")) {
tokenizer.consumeExpectedSymbol(";");
}
} else {
// If it is neither an attribute, nor a media query or instruction - it is probably a sub section...
result.addSubSection(parseSection(false));
}
}
tokenizer.consumeExpectedSymbol("}");
return result;
}
/*
* CSS and therefore als SASS supports a wide range or complex selector strings. The following method
* parses such selectors while performing basic consistency checks
*/
private List parseSelector() {
List selector = new ArrayList();
boolean lastWasId = false;
while (tokenizer.more()) {
if (tokenizer.current().isSymbol("{", ",")) {
if (selector.isEmpty()) {
tokenizer.addError(tokenizer.current(), "Unexpected end of CSS selector");
}
return selector;
} else if (tokenizer.current().isIdentifier() || tokenizer.current().isSpecialIdentifier("#")) {
StringBuilder sb = new StringBuilder(tokenizer.consume().getSource());
while (tokenizer.current().isSymbol(":")) {
sb.append(tokenizer.consume().getSource());
sb.append(tokenizer.consume().getSource());
}
while (tokenizer.current().isSymbol("[")) {
// Consume [
sb.append(tokenizer.consume().getContents());
// Read attribute name
if (!tokenizer.current().isSymbol("]")) {
if (!tokenizer.current().isIdentifier()) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '%s'. Expected an attribute name.",
tokenizer.current().getSource());
}
sb.append(tokenizer.consume().getContents());
}
// Read operator
if (!tokenizer.current().isSymbol("]")) {
if (!tokenizer.current().isSymbol("=", "~=", "|=", "^=", "$=", "*=")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '%s'. Expected an operation.",
tokenizer.current().getSource());
}
sb.append(tokenizer.consume().getTrigger());
}
// Read value
if (!tokenizer.current().isSymbol("]")) {
sb.append(tokenizer.consume().getSource());
}
// Consume ]
if (!tokenizer.current().isSymbol("]")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '%s'. Expected: ']'",
tokenizer.current().getSource());
} else {
sb.append(tokenizer.consume().getContents());
}
}
selector.add(sb.toString());
lastWasId = true;
} else if (tokenizer.current().isSymbol(">", "+", "~")) {
if (!lastWasId || !tokenizer.next().isIdentifier()) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '%s'. A selector path must not contain two consecutive operators.",
tokenizer.current().getSource());
}
selector.add(tokenizer.consume().getSource());
lastWasId = false;
} else {
tokenizer.addError(tokenizer.current(), "Unexpected Token: %s", tokenizer.consume().getSource());
lastWasId = false;
}
}
return selector;
}
/*
* Parses a variable declaration in form of "$variable: value;" or "$variable: value !default;"
*/
private void parseVariableDeclaration() {
Variable var = new Variable();
var.setName(tokenizer.consume().getContents());
tokenizer.consumeExpectedSymbol(":");
var.setValue(parseExpression(true));
if (tokenizer.current().isSymbol("!") && tokenizer.next().hasContent("default")) {
var.setDefaultValue(true);
tokenizer.consume();
tokenizer.consume();
}
result.addVariable(var);
tokenizer.consumeExpectedSymbol(";");
}
/*
* Parses an expression which can be the value of an attribute or media query. Basic numeric operations
* like +,-,*,/,% are supported. Also " " separated lists will be parsed as ValueList
*/
private Expression parseExpression(boolean accepLists) {
Expression result = parseAtom(accepLists);
while (tokenizer.more()) {
if (tokenizer.current().isSymbol("+", "-")) {
result = new Operation(tokenizer.consume().getTrigger(), result, parseAtom(false));
} else if (tokenizer.current().isSymbol("*", "/", "%")) {
String operation = tokenizer.consume().getTrigger();
Expression next = parseAtom(false);
result = joinOperations(result, operation, next);
} else {
if (tokenizer.current().isSymbol() && !tokenizer.current().isSymbol("!")) {
break;
}
if (result instanceof ValueList) {
((ValueList) result).add(parseAtom(accepLists));
} else {
ValueList list = new ValueList();
list.add(result);
list.add(parseAtom(accepLists));
result = list;
}
}
}
return result;
}
/*
* Takes care of operator precedence by modifying the AST appropriately
*/
private Expression joinOperations(Expression result, String operation, Expression next) {
if (!(result instanceof Operation)) {
return new Operation(operation, result, next);
}
Operation farRight = (Operation) result;
while (farRight.getRight() instanceof Operation) {
farRight = (Operation) farRight.getRight();
}
if (!farRight.isProtect() && ("+".equals(farRight.getOperation()) || "-".equals(farRight.getOperation()))) {
farRight.setRight(new Operation(operation, farRight.getRight(), next));
return result;
}
return new Operation(operation, result, next);
}
/*
* Parses an atom. This is either an identifier ("bold"), a number (15px), a string ('OpenSans'), a color
* (#454545) or another expression in braces.
*/
private Expression parseAtom(boolean acceptLists) {
// Parse a number
if (tokenizer.current().isNumber()) {
return new Number(tokenizer.consume().getContents());
}
// Parse a color
if (tokenizer.current().isSpecialIdentifier("#")) {
return new Value(tokenizer.consume().getSource()); //TODO encode color
}
// Parse an identifier or function call
if (tokenizer.current().isIdentifier()) {
if (tokenizer.next().isSymbol("(")) {
// An identifier followed by '(' is a function call...
FunctionCall fun = new FunctionCall();
fun.setName(tokenizer.consume().getContents());
tokenizer.consumeExpectedSymbol("(");
while (tokenizer.more() && !tokenizer.current().isSymbol(")", ";", "{", "}")) {
fun.addParameter(parseExpression(false));
if (tokenizer.current().isSymbol(",")) {
tokenizer.consumeExpectedSymbol(",");
} else if (!tokenizer.current().isSymbol(")")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume()
.getSource() + "'. Expected a comma between the parameters."
);
}
}
tokenizer.consumeExpectedSymbol(")");
return fun;
} else if (tokenizer.next().isSymbol(",") && acceptLists) {
// Parse a value list like Arial,Helvetica
StringBuilder sb = new StringBuilder(tokenizer.consume().getSource());
while (tokenizer.current().isSymbol(",")) {
sb.append(tokenizer.consume().getSource());
if (!tokenizer.current().isSymbol(";", "(", ")", "{", "}")) {
sb.append(tokenizer.consume().getSource());
}
}
return new Value(sb.toString());
}
// Neither function or value list -> simple value
return new Value(tokenizer.consume().getSource());
}
// Parse as variable reference
if (tokenizer.current().isSpecialIdentifier("$")) {
return new VariableReference(tokenizer.consume().getContents());
}
// Parse as string constant
if (tokenizer.current().isString()) {
return new Value(tokenizer.consume().getSource());
}
// Parse as expression in braces
if (tokenizer.current().isSymbol("(")) {
tokenizer.consumeExpectedSymbol("(");
Expression result = parseExpression(true);
tokenizer.consumeExpectedSymbol(")");
if (result instanceof Operation) {
((Operation) result).protect();
}
return result;
}
// Attribute values can be followed by things like "!import" -> make a value list
if (tokenizer.current().isSymbol("!") && tokenizer.next().isIdentifier()) {
tokenizer.consumeExpectedSymbol("!");
return new Value("!" + tokenizer.consume().getContents());
}
// We failed! Report an error and return "" as value (we will fail anyway...)
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume().getSource() + "'. Expected an expression.");
return new Value("");
}
/*
* Parse @mixin which are essentially template secions...
*/
private Mixin parseMixin() {
tokenizer.consumeExpectedKeyword("mixin");
Mixin mixin = new Mixin();
// Parse name
if (tokenizer.current().isIdentifier()) {
mixin.setName(tokenizer.consume().getContents());
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.current()
.getSource() + "'. Expected the name of the mixin as identifier."
);
}
// Parse parameter names...
tokenizer.consumeExpectedSymbol("(");
while (tokenizer.more()) {
if (tokenizer.current().isSymbol("{")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.current()
.getSource() + "'. Expected ')' to complete the parameter list."
);
break;
}
if (tokenizer.current().isSymbol(")")) {
tokenizer.consumeExpectedSymbol(")");
break;
}
if (tokenizer.current().isSpecialIdentifier("$")) {
mixin.addParameter(tokenizer.consume().getContents());
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume()
.getSource() + "'. Expected a parameter name like $parameter."
);
}
if (tokenizer.current().isSymbol(",")) {
tokenizer.consumeExpectedSymbol(",");
} else if (!tokenizer.current().isSymbol(")")) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume()
.getSource() + "'. Expected a comma between the parameter names."
);
}
}
// Parse attributes - sub sections are not expected...
tokenizer.consumeExpectedSymbol("{");
while (tokenizer.more()) {
if (tokenizer.current().isSymbol("}")) {
tokenizer.consumeExpectedSymbol("}");
return mixin;
}
if (tokenizer.current().isIdentifier() && tokenizer.next().isSymbol(":")) {
Attribute attr = new Attribute(tokenizer.consume().getContents());
tokenizer.consumeExpectedSymbol(":");
attr.setExpression(parseExpression(true));
mixin.addAttribute(attr);
if (tokenizer.current().isSymbol(";") || !tokenizer.next().isSymbol("}")) {
tokenizer.consumeExpectedSymbol(";");
}
} else {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.consume()
.getSource() + "'. Expected an attribute definition."
);
}
}
tokenizer.consumeExpectedSymbol("}");
return mixin;
}
/*
* Parses an import statement like "@import 'test';"
*/
private void parseImport() {
tokenizer.consumeExpectedKeyword("import");
if (!tokenizer.current().isString()) {
tokenizer.addError(tokenizer.current(),
"Unexpected token: '" + tokenizer.current()
.getSource() + "'. Expected a string constant naming an import file."
);
} else {
result.addImport(tokenizer.consume().getContents());
}
tokenizer.consumeExpectedSymbol(";");
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy