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|
#[doc="Constructs a list of 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};
import parser::css_lexer::{Token, StartDescription, EndDescription,
Descendant, Child, Sibling,
Comma, Element, Attr, Description,
Eof};
import comm::recv;
import option::is_none;
import util::color::parsing::parse_color;
import vec::push;
type TokenReader = {stream : port<Token>, mut lookahead : option<Token>};
impl methods for TokenReader {
fn get() -> Token {
alt copy self.lookahead {
some(tok) { self.lookahead = none; copy tok }
none { recv(self.stream) }
}
}
fn unget(-tok : Token) {
assert is_none(self.lookahead);
self.lookahead = some(tok);
}
}
fn parse_element(reader : TokenReader) -> option<~style::Selector> {
// Get the current element type
let elmt_name = alt reader.get() {
Element(tag) { copy tag }
Eof { ret none; }
_ { fail "Expected an element" }
};
let mut attr_list = ~[];
// Get the attributes associated with that element
loop {
let tok = reader.get();
alt tok {
Attr(attr) { push(attr_list, copy attr); }
StartDescription | Descendant | Child | Sibling | Comma {
reader.unget(tok);
break;
}
Eof { ret none; }
Element(_) { fail "Unexpected second element without "
+ "relation to first element"; }
EndDescription { fail "Unexpected '}'"; }
Description(_, _) { fail "Unexpected description"; }
}
}
ret some(~style::Element(elmt_name, attr_list));
}
fn parse_rule(reader : TokenReader) -> option<~style::Rule> {
let mut sel_list = ~[];
let mut desc_list = ~[];
// Collect all the selectors that this rule applies to
loop {
let mut cur_sel;
alt parse_element(reader) {
some(elmt) { cur_sel = copy elmt; }
none { ret none; } // we hit an eof in the middle of a rule
}
loop {
let tok = reader.get();
alt tok {
Descendant {
alt parse_element(reader) {
some(elmt) {
let built_sel <- cur_sel;
let new_sel = copy elmt;
cur_sel <- ~style::Descendant(built_sel, new_sel)
}
none { ret none; }
}
}
Child {
alt parse_element(reader) {
some(elmt) {
let built_sel <- cur_sel;
let new_sel = copy elmt;
cur_sel <- ~style::Child(built_sel, new_sel)
}
none { ret none; }
}
}
Sibling {
alt parse_element(reader) {
some(elmt) {
let built_sel <- cur_sel;
let new_sel = copy elmt;
cur_sel <- ~style::Sibling(built_sel, new_sel)
}
none { ret none; }
}
}
StartDescription {
let built_sel <- cur_sel;
push(sel_list, built_sel);
reader.unget(StartDescription);
break;
}
Comma {
let built_sel <- cur_sel;
push(sel_list, built_sel);
reader.unget(Comma);
break;
}
Attr(_) | EndDescription | Element(_) | Description(_, _) {
fail #fmt["Unexpected token %? in elements", tok];
}
Eof { ret none; }
}
}
// check if we should break out of the nesting loop as well
let tok = reader.get();
alt tok {
StartDescription { break; }
Comma { }
_ { reader.unget(tok); }
}
}
// Get the description to be applied to the selector
loop {
let tok = reader.get();
alt tok {
EndDescription { break; }
Description(prop, val) {
alt prop {
"font-size" {
// TODO, support more ways to declare a font size than # pt
assert val.ends_with("pt");
let num = val.substr(0u, val.len() - 2u);
alt uint::from_str(num) {
some(n) { push(desc_list, FontSize(n)); }
none { fail "Nonnumber provided as font size"; }
}
}
"display" {
alt val {
"inline" { push(desc_list, Display(DisInline)); }
"block" { push(desc_list, Display(DisBlock)); }
"none" { push(desc_list, Display(DisNone)); }
_ { #debug["Recieved unknown display value '%s'", val]; }
}
}
"color" {
push(desc_list, TextColor(parse_color(val)));
}
"background-color" {
push(desc_list, BackgroundColor(parse_color(val)));
}
_ { #debug["Recieved unknown style property '%s'", val]; }
}
}
Eof { ret none; }
StartDescription | Descendant | Child | Sibling
| Comma | Element(_) | Attr(_) {
fail #fmt["Unexpected token %? in description", tok];
}
}
}
ret some(~(sel_list, desc_list));
}
fn build_stylesheet(stream : port<Token>) -> ~[~style::Rule] {
let mut rule_list = ~[];
let reader = {stream : stream, mut lookahead : none};
loop {
alt parse_rule(reader) {
some(rule) { push(rule_list, copy rule); }
none { break; }
}
}
ret rule_list;
}
|
