This class provides a collection of various functions to transform, parse, and convert latex code to and from utf8 and other encodings.
$latex_special_chars_dictionary : array
An associative array of regular expressions that match latex code and utf8 representations of the respective symbol they represent
As PHP does not allow the initialization of static variables from static member methods we have to initialize this array to null. You may thus never use this variable directly, instead use the getter method below.
$latex_special_chars_reverse_dictionary :
Associative array of utf8 representations and their respective LaTeX representations.
In some cases we need to generate LaTeX code from utf-8 encoded strings containing special characters. This array helps in doing this.
$utf8_to_ascii_dictionary :
Associative array of utf8 representations and their closest ascii characters.
In some cases we need to generate ascii strings from utf-8 encoded strings containing special characters. This array helps in doing this.
$additional_default_macros : array
Additional macros.
Array of default macros that we always want to expand, irrespective of whether they appeared in a LaTeX file.
get_latex_special_chars_dictionary()
Get the $latex_special_chars_dictionary.
We are dealing with a lot of LaTeX code in wich special characters are LaTeX encoded. On our website we want to display them in a pretty way. The following is a (more or less complete) mapping of LaTeX encodigs into utf-8 characters whenever such a character is available. This list must only contain latex macros that contain a \ as for preformance reasons replacing is stopped once all \ have been eliminated. Also there is a negative look must be added when using this dictionary to prevent replacements in cases such as \v{a}.
expand_cite_to_html(string $text, string $bbl)
Expand \cite{} commands to html code.
The resulting html code makes every \cite a clickable hyperlink to the correspnding entry in the bibliograhy.
| string | $text | The text in which \cite commands are to be expanded |
| string | $bbl | The bbl code of the bibliography that contains the corresponding bibliography entries. |
normalize_whitespace_and_linebreak_characters(string $text, boolean $single_line = true, boolean $remove_extra_newlines = false)
Normalized white space and line break characters.
| string | $text | LaTeX text to normalize. |
| boolean | $single_line | Whether to output a single-line text. |
| boolean | $remove_extra_newlines | If true, single newlines are replaced by space and any number of more than two successive newlines are replaced by exactly two newlines. |
latex_to_utf8_outside_math_mode(string $latex_text, boolean $clean = true) : string
Convert LaTeX code to utf8, leaving alone everything within math mode.
Does not attempt to deal with commands that cannot be reasonably represented in utf8, such as \small, \newblock, \emph, ...
Leaves mathematical formulas enclosed in $...$ (and other math mode delimiters such as $$...$$,...) intact so that they can be displayed nicely using MathJax. This function turns various the math modes into linline mode $a+b$.
| string | $latex_text | Latex code whose non-math part is to be converted to utf8 |
| boolean | $clean | Whether to perform some cleanup at the end. |
A utf8 approximation to $latex_text
preg_split_at_latex_math_mode_delimters(string $text, integer $limit = -1, integer $flags)
Preg split LaTeX code at math mode delimters.
If $text is well formed, Odd parts of the resulting array are outside math mode and even parts are inside math mode. If $fags is not specified or set to 0 the delimiters are stripped.
| string | $text | Text to be split at LaTeX math mode delimiters such as $...$ [...] (...). |
| integer | $limit | If specified, then only substrings up to limit are returned with the rest of the string being placed in the last substring. A limit of -1 or 0 means "no limit" and, as is standard across PHP, you can use NULL to skip to the flags parameter. |
| integer | $flags | Flags can be any combination of valid preg_split flags. Defaults to 0. |
strpos_outside_math_mode(string $latex_text, string $string)
Strpos in latex code, but only taking into account the part of code that is not in math mode. This function uses the multi byte safe mb_str_pos() function.
| string | $latex_text | Latex text in whose non-math parts the string is to be found. |
| string | $string | String to be found. |
preg_match_outside_math_mode(string $pattern, string $subject, array $matches = array(), integer $flags, integer $offset) : integer
Preg match in latex code, but only taking into account the part of code that is not in math mode.
| string | $pattern | Reular expression to match against. |
| string | $subject | Latex text in whose non-math parts the expression is to be found. |
| array | $matches | If matches is provided, then it is filled with the results of search. $matches[0] will contain an array of texts that matched the full pattern, $matches[1] will have an array of the texts that matched the first captured parenthesized subpattern, and so on. |
| integer | $flags | Flags as in preg_match(). |
| integer | $offset | Place from which to start the search (in bytes) within each segment of subjbect that is outisde math mode. |
False in case an error occurred during any of the matches. Alternatively returns the total number of segments in which a match was found.
parse_bbl(string $bbl)
Parse bbl code of potentially multiple bibliographies.
Parses bbl code produced by either bibtex or biblatex as well as such written by authors by hand. $bbl may be a concatenation of multiple bibliographies.
| string | $bbl | Bibliography or concatenation of bibliographies in .bbl format as it is produced by BibTeX, Biber, and BibLaTeX. |
extract_latex_macros(string $latex_source)
Extracts LaTeX command definitions from latex code.
Extracts LaTeX command definitions from latex code.
Supported are:
newcommand providecommand renewcommand renewcommand. def DeclarePairedDelimiter
For a command such as
\newcommand{\myvec}[1]{\vec{#1}}
the resulting definition is of the following form:
Full match 0-22 \newcommand{\myvec}[1]
Group 1. 1-11 newcommand
Group 2. 12-18 \myvec
Group 3. 19-22 [1]
Group 4. 22-22 ` (in case a default is set making an argument optional) Group 5. 23-31\vec{#1}`
| string | $latex_source | LaTeX source code from with the macro definitions are to be extracted. |
get_special_macros_to_ignore_in_bbl()
Get special macros we sometimes want to ignore in expansion.
Some macros are better kept unexpended even if the authors have manually re-defined them, because we need them to more efficiently parse the latex code (i.e., to identify DOIs or URLs).
expand_latex_macros(array $macro_definitions, string $text)
Expand LaTeX macros.
Attempts to expands all macros in $text for which a definition is given in $macro_definitions.
Expects definitions like those produced by self::extract_latex_macros().
| array | $macro_definitions | Array of macro definitions. |
| string | $text | Text containing LaTeX macros that are to be expanded. |