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#[doc="Constructs a list of css style rules from a token stream"]
// TODO: fail according to the css spec instead of failing when things
// are not as expected
import dom::style;
import style::{DisInline, DisBlock, DisNone, Display, TextColor, BackgroundColor, FontSize,
Height, Width, StyleDeclaration, Selector};
import parser::css_lexer::{Token, StartDescription, EndDescription,
Descendant, Child, Sibling,
Comma, Element, Attr, Description,
Eof};
import comm::recv;
import option::{map, is_none};
import vec::push;
import parser::parser_util::{parse_display_type, parse_font_size, parse_size};
import util::color::parsing::parse_color;
import vec::push;
type TokenReader = {stream : pipes::Port<Token>, mut lookahead : Option<Token>};
trait TokenReaderMethods {
fn get() -> Token;
fn unget(-tok : Token);
}
impl TokenReader : TokenReaderMethods {
fn get() -> Token {
match copy self.lookahead {
Some(tok) => { self.lookahead = None; copy tok }
None => { self.stream.recv() }
}
}
fn unget(-tok : Token) {
assert is_none(self.lookahead);
self.lookahead = Some(tok);
}
}
trait ParserMethods {
fn parse_element() -> Option<~style::Selector>;
fn parse_selector() -> Option<~[~Selector]>;
fn parse_description() -> Option<~[StyleDeclaration]>;
fn parse_rule() -> Option<~style::Rule>;
}
impl TokenReader : ParserMethods {
fn parse_element() -> Option<~style::Selector> {
// Get the current element type
let elmt_name = match self.get() {
Element(tag) => { copy tag }
Eof => { return None; }
_ => { fail ~"Expected an element" }
};
let mut attr_list = ~[];
// Get the attributes associated with that element
loop {
let tok = self.get();
match tok {
Attr(attr) => { push(attr_list, copy attr); }
StartDescription | Descendant | Child | Sibling | Comma => {
self.unget(tok);
break;
}
Eof => { return None; }
Element(_) => fail ~"Unexpected second element without relation to first element",
EndDescription => fail ~"Unexpected '}'",
Description(_, _) => fail ~"Unexpected description"
}
}
return Some(~style::Element(elmt_name, attr_list));
}
fn parse_selector() -> Option<~[~Selector]> {
let mut sel_list = ~[];
// Collect all the selectors that this rule applies to
loop {
let mut cur_sel;
match self.parse_element() {
Some(elmt) => { cur_sel = copy elmt; }
None => { return None; } // we hit an eof in the middle of a rule
}
loop {
let tok = self.get();
let built_sel <- cur_sel;
match tok {
Descendant => {
match self.parse_element() {
Some(elmt) => {
let new_sel = copy elmt;
cur_sel <- ~style::Descendant(built_sel, new_sel)
}
None => { return None; }
}
}
Child => {
match self.parse_element() {
Some(elmt) => {
let new_sel = copy elmt;
cur_sel <- ~style::Child(built_sel, new_sel)
}
None => { return None; }
}
}
Sibling => {
match self.parse_element() {
Some(elmt) => {
let new_sel = copy elmt;
cur_sel <- ~style::Sibling(built_sel, new_sel)
}
None => { return None; }
}
}
StartDescription => {
push(sel_list, built_sel);
self.unget(StartDescription);
break;
}
Comma => {
push(sel_list, built_sel);
self.unget(Comma);
break;
}
Attr(_) | EndDescription | Element(_) | Description(_, _) => {
fail #fmt["Unexpected token %? in elements", tok];
}
Eof => { return None; }
}
}
// check if we should break out of the nesting loop as well
// TODO: fix this when rust gets labelled loops
let tok = self.get();
match tok {
StartDescription => { break; }
Comma => { }
_ => { self.unget(tok); }
}
}
return Some(sel_list);
}
fn parse_description() -> Option<~[StyleDeclaration]> {
let mut desc_list : ~[StyleDeclaration]= ~[];
// Get the description to be applied to the selector
loop {
let tok = self.get();
match tok {
EndDescription => { break; }
Description(prop, val) => {
let desc = match prop {
// TODO: have color parsing return an option instead of a real value
~"background-color" => parse_color(val).map(|res| BackgroundColor(res)),
~"color" => parse_color(val).map(|res| TextColor(res)),
~"display" => parse_display_type(val).map(|res| Display(res)),
~"font-size" => parse_font_size(val).map(|res| FontSize(res)),
~"height" => parse_size(val).map(|res| Height(res)),
~"width" => parse_size(val).map(|res| Width(res)),
_ => { #debug["Recieved unknown style property '%s'", val]; None }
};
desc.map(|res| push(desc_list, res));
}
Eof => { return None; }
StartDescription | Descendant | Child | Sibling | Comma | Element(_) | Attr(_) => {
fail #fmt["Unexpected token %? in description", tok];
}
}
}
return Some(desc_list);
}
fn parse_rule() -> Option<~style::Rule> {
// TODO: get rid of copies once match move works
let sel_list = match self.parse_selector() {
Some(list) => { copy list }
None => { return None; }
};
#debug("sel_list: %?", sel_list);
// Get the description to be applied to the selector
let desc_list = match self.parse_description() {
Some(list) => { copy list }
None => { return None; }
};
#debug("desc_list: %?", desc_list);
return Some(~(sel_list, desc_list));
}
}
fn build_stylesheet(+stream : pipes::Port<Token>) -> ~[~style::Rule] {
let mut rule_list = ~[];
let reader = {stream : stream, mut lookahead : None};
loop {
match reader.parse_rule() {
Some(rule) => { push(rule_list, copy rule); }
None => { break; }
}
}
return rule_list;
}
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