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cssparser.go
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cssparser.go
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package parser
import (
"strings"
"unicode"
"github.com/a-h/parse"
)
// CSS.
// CSS Parser.
var cssParser = parse.Func(func(pi *parse.Input) (r CSSTemplate, ok bool, err error) {
r = CSSTemplate{
Properties: []CSSProperty{},
}
// Parse the name.
var exp cssExpression
if exp, ok, err = cssExpressionParser.Parse(pi); err != nil || !ok {
return
}
r.Name = exp.Name
for {
var cssProperty CSSProperty
// Try for an expression CSS declaration.
// background-color: { constants.BackgroundColor };
cssProperty, ok, err = expressionCSSPropertyParser.Parse(pi)
if err != nil {
return
}
if ok {
r.Properties = append(r.Properties, cssProperty)
continue
}
// Try for a constant CSS declaration.
// color: #ffffff;
cssProperty, ok, err = constantCSSPropertyParser.Parse(pi)
if err != nil {
return
}
if ok {
r.Properties = append(r.Properties, cssProperty)
continue
}
// Eat any whitespace.
if _, ok, err = parse.OptionalWhitespace.Parse(pi); err != nil || !ok {
return
}
// Try for }
if _, ok, err = closeBraceWithOptionalPadding.Parse(pi); err != nil || !ok {
err = parse.Error("css property expression: missing closing brace", pi.Position())
return
}
return r, true, nil
}
})
// css Func() {
type cssExpression struct {
Name Expression
}
var cssExpressionStartParser = parse.String("css ")
var cssExpressionNameParser = parse.Func(func(in *parse.Input) (name string, ok bool, err error) {
var c string
if c, ok = in.Peek(1); !ok || !unicode.IsLetter(rune(c[0])) {
return
}
prefix, _, _ := parse.Letter.Parse(in)
suffix, _, _ := parse.AtMost(1000, parse.Any(parse.Letter, parse.ZeroToNine)).Parse(in)
return prefix + strings.Join(suffix, ""), true, nil
})
var cssExpressionParser = parse.Func(func(pi *parse.Input) (r cssExpression, ok bool, err error) {
// Check the prefix first.
if _, ok, err = cssExpressionStartParser.Parse(pi); err != nil || !ok {
return
}
// Once we have the prefix, we must have a name and parameters.
// Read the name of the function.
from := pi.Position()
// If there's no match, the name wasn't correctly terminated.
var name string
if name, ok, err = cssExpressionNameParser.Parse(pi); err != nil || !ok {
err = parse.Error("css expression: invalid name", pi.Position())
return
}
r.Name = NewExpression(name, from, pi.Position())
// Eat the open bracket.
if _, ok, err = openBracket.Parse(pi); err != nil || !ok {
err = parse.Error("css expression: parameters missing open bracket", pi.Position())
return
}
// Check there's no parameters.
from = pi.Position()
if _, ok, err = parse.StringUntil(closeBracket).Parse(pi); err != nil {
return
}
// If there's no match, the name wasn't correctly terminated.
if !ok {
return r, ok, parse.Error("css expression: parameters missing close bracket", pi.Position())
}
if pi.Index()-int(from.Index) > 0 {
return r, ok, parse.Error("css expression: found unexpected parameters", pi.Position())
}
// Eat ") {".
if _, ok, err = expressionFuncEnd.Parse(pi); err != nil || !ok {
err = parse.Error("css expression: unterminated (missing ') {')", pi.Position())
return
}
// Expect a newline.
if _, ok, err = parse.NewLine.Parse(pi); err != nil || !ok {
err = parse.Error("css expression: missing terminating newline", pi.Position())
return
}
return r, true, nil
})
// CSS property name parser.
var cssPropertyNameFirst = "abcdefghijklmnopqrstuvwxyz-"
var cssPropertyNameSubsequent = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-"
var cssPropertyNameParser = parse.Func(func(in *parse.Input) (name string, ok bool, err error) {
start := in.Position()
var prefix, suffix string
if prefix, ok, err = parse.RuneIn(cssPropertyNameFirst).Parse(in); err != nil || !ok {
return
}
if suffix, ok, err = parse.StringUntil(parse.RuneNotIn(cssPropertyNameSubsequent)).Parse(in); err != nil || !ok {
in.Seek(start.Index)
return
}
if len(suffix)+1 > 128 {
ok = false
err = parse.Error("css property names must be < 128 characters long", in.Position())
return
}
return prefix + suffix, true, nil
})
// background-color: {%= constants.BackgroundColor %};
var expressionCSSPropertyParser = parse.Func(func(pi *parse.Input) (r ExpressionCSSProperty, ok bool, err error) {
start := pi.Index()
// Optional whitespace.
if _, ok, err = parse.OptionalWhitespace.Parse(pi); err != nil || !ok {
return
}
// Property name.
if r.Name, ok, err = cssPropertyNameParser.Parse(pi); err != nil || !ok {
pi.Seek(start)
return
}
// <space>:<space>
if _, ok, err = parse.All(parse.OptionalWhitespace, parse.Rune(':'), parse.OptionalWhitespace).Parse(pi); err != nil || !ok {
pi.Seek(start)
return
}
// { string }
var se Node
if se, ok, err = stringExpression.Parse(pi); err != nil || !ok {
pi.Seek(start)
return
}
r.Value = se.(StringExpression)
// ;
if _, ok, err = parse.String(";").Parse(pi); err != nil || !ok {
err = parse.Error("missing expected semicolon (;)", pi.Position())
return
}
// \n
if _, ok, err = parse.NewLine.Parse(pi); err != nil || !ok {
err = parse.Error("missing expected linebreak", pi.Position())
return
}
return r, true, nil
})
// background-color: #ffffff;
var constantCSSPropertyParser = parse.Func(func(pi *parse.Input) (r ConstantCSSProperty, ok bool, err error) {
start := pi.Index()
// Optional whitespace.
if _, ok, err = parse.OptionalWhitespace.Parse(pi); err != nil || !ok {
return
}
// Property name.
if r.Name, ok, err = cssPropertyNameParser.Parse(pi); err != nil || !ok {
pi.Seek(start)
return
}
// <space>:<space>
if _, ok, err = parse.All(parse.OptionalWhitespace, parse.Rune(':'), parse.OptionalWhitespace).Parse(pi); err != nil || !ok {
pi.Seek(start)
return
}
// Everything until ';\n'
untilEnd := parse.All(
parse.OptionalWhitespace,
parse.Rune(';'),
parse.NewLine,
)
if r.Value, ok, err = parse.StringUntil(untilEnd).Parse(pi); err != nil || !ok {
err = parse.Error("missing expected semicolon and linebreak (;\\n", pi.Position())
return
}
// Chomp the ;\n
if _, ok, err = untilEnd.Parse(pi); err != nil || !ok {
err = parse.Error("failed to chomp semicolon and linebreak (;\\n)", pi.Position())
return
}
return r, true, nil
})