private static bool TryParseHtmlTagDeclaration(ref StringSlice text, StringBuilder builder)
{
var c = text.CurrentChar;
bool hasAlpha = false;
while (c.IsAlphaUpper())
{
builder.Append(c);
c = text.NextChar();
hasAlpha = true;
}
if (!hasAlpha || !c.IsWhitespace())
{
return(false);
}
// Regexp: "\\![A-Z]+\\s+[^>\\x00]*>"
while (true)
{
builder.Append(c);
c = text.NextChar();
if (c == '\0')
{
return(false);
}
if (c == '>')
{
text.NextChar();
builder.Append('>');
return(true);
}
}
}
private static bool TryParseHtmlTagCData(ref StringSlice text, ref ValueStringBuilder builder)
{
if (text.Match("[CDATA["))
{
builder.Append("[CDATA[");
text.Start += 6;
char c = '\0';
while (true)
{
var pc = c;
c = text.NextChar();
if (c == '\0')
{
return(false);
}
builder.Append(c);
if (c == ']' && pc == ']' && text.PeekChar() == '>')
{
text.SkipChar();
text.SkipChar();
builder.Append('>');
return(true);
}
}
}
return(false);
}
internal static bool TryParseHtmlCloseTag(ref StringSlice text, StringBuilder builder)
{
// </[A-Za-z][A-Za-z0-9]+\s*>
builder.Append('/');
var c = text.NextChar();
if (!c.IsAlpha())
{
return(false);
}
builder.Append(c);
bool skipSpaces = false;
while (true)
{
c = text.NextChar();
if (c == '>')
{
text.NextChar();
builder.Append('>');
return(true);
}
if (skipSpaces)
{
if (c != ' ')
{
break;
}
}
else if (c == ' ')
{
skipSpaces = true;
}
else if (!(c.IsAlphaNumeric() || c == '-'))
{
break;
}
builder.Append(c);
}
return(false);
}
public static bool TryParseHtmlTag(ref StringSlice text, StringBuilder builder)
{
if (builder is null)
{
ThrowHelper.ArgumentNullException(nameof(builder));
}
var c = text.CurrentChar;
if (c != '<')
{
return(false);
}
c = text.NextChar();
builder.Append('<');
switch (c)
{
case '/':
return(TryParseHtmlCloseTag(ref text, builder));
case '?':
return(TryParseHtmlTagProcessingInstruction(ref text, builder));
case '!':
builder.Append(c);
c = text.NextChar();
if (c == '-')
{
return(TryParseHtmlTagHtmlComment(ref text, builder));
}
if (c == '[')
{
return(TryParseHtmlTagCData(ref text, builder));
}
return(TryParseHtmlTagDeclaration(ref text, builder));
}
return(TryParseHtmlTagOpenTag(ref text, builder));
}
private static bool TryParseHtmlTagHtmlComment(ref StringSlice text, StringBuilder builder)
{
var c = text.NextChar();
if (c != '-')
{
return(false);
}
builder.Append('-');
builder.Append('-');
if (text.PeekChar() == '>')
{
return(false);
}
var countHyphen = 0;
while (true)
{
c = text.NextChar();
if (c == '\0')
{
return(false);
}
if (countHyphen == 2)
{
if (c == '>')
{
builder.Append('>');
text.NextChar();
return(true);
}
return(false);
}
countHyphen = c == '-' ? countHyphen + 1 : 0;
builder.Append(c);
}
}
private static bool TryParseHtmlTagCData(ref StringSlice text, StringBuilder builder)
{
builder.Append('[');
var c = text.NextChar();
if (c == 'C' &&
text.NextChar() == 'D' &&
text.NextChar() == 'A' &&
text.NextChar() == 'T' &&
text.NextChar() == 'A' &&
(c = text.NextChar()) == '[')
{
builder.Append("CDATA[");
while (true)
{
var pc = c;
c = text.NextChar();
if (c == '\0')
{
return(false);
}
if (c == ']' && pc == ']')
{
builder.Append(']');
c = text.NextChar();
if (c == '>')
{
builder.Append('>');
text.NextChar();
return(true);
}
if (c == '\0')
{
return(false);
}
}
builder.Append(c);
}
}
return(false);
}
private static bool TryParseHtmlTag(ref StringSlice text, ref ValueStringBuilder builder)
{
var c = text.CurrentChar;
if (c != '<')
{
return(false);
}
c = text.NextChar();
builder.Append('<');
switch (c)
{
case '/':
return(TryParseHtmlCloseTag(ref text, ref builder));
case '?':
return(TryParseHtmlTagProcessingInstruction(ref text, ref builder));
case '!':
builder.Append(c);
c = text.NextChar();
if (c == '-')
{
return(TryParseHtmlTagHtmlComment(ref text, ref builder));
}
if (c == '[')
{
return(TryParseHtmlTagCData(ref text, ref builder));
}
return(TryParseHtmlTagDeclaration(ref text, ref builder));
}
return(TryParseHtmlTagOpenTag(ref text, ref builder));
}
private static bool TryParseHtmlTagProcessingInstruction(ref StringSlice text, StringBuilder builder)
{
builder.Append('?');
var prevChar = '\0';
while (true)
{
var c = text.NextChar();
if (c == '\0')
{
return(false);
}
if (c == '>' && prevChar == '?')
{
builder.Append('>');
text.NextChar();
return(true);
}
prevChar = c;
builder.Append(c);
}
}
public static bool TryParseInlineLink(ref StringSlice text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan)
{
// 1. An inline link consists of a link text followed immediately by a left parenthesis (,
// 2. optional whitespace, TODO: specs: is it whitespace or multiple whitespaces?
// 3. an optional link destination,
// 4. an optional link title separated from the link destination by whitespace,
// 5. optional whitespace, TODO: specs: is it whitespace or multiple whitespaces?
// 6. and a right parenthesis )
bool isValid = false;
var c = text.CurrentChar;
link = null;
title = null;
linkSpan = SourceSpan.Empty;
titleSpan = SourceSpan.Empty;
// 1. An inline link consists of a link text followed immediately by a left parenthesis (,
if (c == '(')
{
text.NextChar();
text.TrimStart();
var pos = text.Start;
if (TryParseUrl(ref text, out link))
{
linkSpan.Start = pos;
linkSpan.End = text.Start - 1;
if (linkSpan.End < linkSpan.Start)
{
linkSpan = SourceSpan.Empty;
}
int spaceCount;
text.TrimStart(out spaceCount);
var hasWhiteSpaces = spaceCount > 0;
c = text.CurrentChar;
if (c == ')')
{
isValid = true;
}
else if (hasWhiteSpaces)
{
c = text.CurrentChar;
pos = text.Start;
if (c == ')')
{
isValid = true;
}
else if (TryParseTitle(ref text, out title))
{
titleSpan.Start = pos;
titleSpan.End = text.Start - 1;
if (titleSpan.End < titleSpan.Start)
{
titleSpan = SourceSpan.Empty;
}
text.TrimStart();
c = text.CurrentChar;
if (c == ')')
{
isValid = true;
}
}
}
}
}
if (isValid)
{
// Skip ')'
text.NextChar();
title = title ?? String.Empty;
}
return(isValid);
}
public static bool TryParseAutolink(ref StringSlice text, out string link, out bool isEmail)
{
link = null;
isEmail = false;
var c = text.CurrentChar;
if (c != '<')
{
return(false);
}
// An absolute URI, for these purposes, consists of a scheme followed by a colon (:)
// followed by zero or more characters other than ASCII whitespace and control characters, <, and >.
// If the URI includes these characters, they must be percent-encoded (e.g. %20 for a space).
// A URI that would end with a full stop (.) is treated instead as ending immediately before the full stop.
// a scheme is any sequence of 2–32 characters
// beginning with an ASCII letter
// and followed by any combination of ASCII letters, digits, or the symbols plus (”+”), period (”.”), or hyphen (”-”).
// An email address, for these purposes, is anything that matches the non-normative regex from the HTML5 spec:
// /^
// [a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+
// @
// [a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?
// (?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
c = text.NextChar();
// -1: scan email
// 0: scan uri or email
// +1: scan uri
int state = 0;
if (!c.IsAlpha())
{
// We may have an email char?
if (c.IsDigit() || CharHelper.IsEmailUsernameSpecialChar(c))
{
state = -1;
}
else
{
return(false);
}
}
var builder = StringBuilderCache.Local();
// ****************************
// 1. Scan scheme or user email
// ****************************
builder.Append(c);
while (true)
{
c = text.NextChar();
// Chars valid for both scheme and email
var isSpecialChar = c == '+' || c == '.' || c == '-';
var isValidChar = c.IsAlphaNumeric() || isSpecialChar;
if (state <= 0 && CharHelper.IsEmailUsernameSpecialChar(c))
{
isValidChar = true;
// If this is not a special char valid also for url scheme, then we have an email
if (!isSpecialChar)
{
state = -1;
}
}
if (isValidChar)
{
// a scheme is any sequence of 2–32 characters
if (state > 0 && builder.Length >= 32)
{
builder.Length = 0;
return(false);
}
builder.Append(c);
}
else if (c == ':')
{
if (state < 0 || builder.Length <= 2)
{
builder.Length = 0;
return(false);
}
state = 1;
break;
}
else if (c == '@')
{
if (state > 0)
{
builder.Length = 0;
return(false);
}
state = -1;
break;
}
else
{
builder.Length = 0;
return(false);
}
}
// append ':' or '@'
builder.Append(c);
if (state < 0)
{
isEmail = true;
// scan an email
// [a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?
// (?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
bool hasMinus = false;
int domainCharCount = 0;
char pc = '\0';
while (true)
{
c = text.NextChar();
if (c == '>')
{
if (domainCharCount == 0 || hasMinus)
{
break;
}
text.NextChar();
link = builder.ToString();
builder.Length = 0;
return(true);
}
if (c.IsAlphaNumeric() || (domainCharCount > 0 && (hasMinus = c == '-')))
{
domainCharCount++;
if (domainCharCount > 63)
{
break;
}
}
else if (c == '.')
{
if (pc == '.' || pc == '-')
{
break;
}
domainCharCount = 0;
hasMinus = false;
}
else
{
break;
}
builder.Append(c);
}
}
else
{
// scan an uri
// An absolute URI, for these purposes, consists of a scheme followed by a colon (:)
// followed by zero or more characters other than ASCII whitespace and control characters, <, and >.
// If the URI includes these characters, they must be percent-encoded (e.g. %20 for a space).
while (true)
{
c = text.NextChar();
if (c == '\0')
{
break;
}
if (c == '>')
{
text.NextChar();
link = builder.ToString();
builder.Length = 0;
return(true);
}
// Chars valid for both scheme and email
if (c > ' ' && c < 127 && c != '<')
{
builder.Append(c);
}
else
{
break;
}
}
}
builder.Length = 0;
return(false);
}
internal static bool TryParseHtmlTagOpenTag(ref StringSlice text, StringBuilder builder)
{
var c = text.CurrentChar;
// Parse the tagname
if (!c.IsAlpha())
{
return(false);
}
builder.Append(c);
while (true)
{
c = text.NextChar();
if (c.IsAlphaNumeric() || c == '-')
{
builder.Append(c);
}
else
{
break;
}
}
bool hasAttribute = false;
while (true)
{
var hasWhitespaces = false;
// Skip any whitespaces
while (c.IsWhitespace())
{
builder.Append(c);
c = text.NextChar();
hasWhitespaces = true;
}
switch (c)
{
case '\0':
return(false);
case '>':
text.NextChar();
builder.Append(c);
return(true);
case '/':
builder.Append('/');
c = text.NextChar();
if (c != '>')
{
return(false);
}
text.NextChar();
builder.Append('>');
return(true);
case '=':
if (!hasAttribute)
{
return(false);
}
builder.Append('=');
// Skip any spaces after
c = text.NextChar();
while (c.IsWhitespace())
{
builder.Append(c);
c = text.NextChar();
}
// Parse a quoted string
if (c == '\'' || c == '\"')
{
builder.Append(c);
char openingStringChar = c;
while (true)
{
c = text.NextChar();
if (c == '\0')
{
return(false);
}
if (c != openingStringChar)
{
builder.Append(c);
}
else
{
break;
}
}
builder.Append(c);
c = text.NextChar();
}
else
{
// Parse until we match a space or a special html character
int matchCount = 0;
while (true)
{
if (c == '\0')
{
return(false);
}
if (c == ' ' || c == '\n' || c == '"' || c == '\'' || c == '=' || c == '<' || c == '>' || c == '`')
{
break;
}
matchCount++;
builder.Append(c);
c = text.NextChar();
}
// We need at least one char after '='
if (matchCount == 0)
{
return(false);
}
}
hasAttribute = false;
continue;
default:
if (!hasWhitespaces)
{
return(false);
}
// Parse the attribute name
if (!(c.IsAlpha() || c == '_' || c == ':'))
{
return(false);
}
builder.Append(c);
while (true)
{
c = text.NextChar();
if (c.IsAlphaNumeric() || c == '_' || c == ':' || c == '.' || c == '-')
{
builder.Append(c);
}
else
{
break;
}
}
hasAttribute = true;
break;
}
}
}
