7. DISPLAY MODES

The display mode also affects tag lookup, and image-dependent operations such as determining the column number of the cursor's location, and moving the cursor vertically.

You can list the supported display modes by giving the ":display" command without any arguments. Typically, the supported modes will include the following:

.--------.----------------------------------------------.
|  MODE  | DESCRIPTION                                  |
|--------|----------------------------------------------|
| normal | Traditional vi, displays plain ASCII         |
| syntax | Like "normal" but does syntax coloring       |
| hex    | Interactive hex dump, good for binary files  |
| html   | Simple Web page formatter                    |
| man    | Simple Man page formatter, like "nroff -man" |
| tex    | Simple subset of the TeX formatter           |
^--------^----------------------------------------------^

Elvis 2.1 allows each window to be in a different display mode. You can manually change a window's display mode via the ":display mode" command, where mode is the name of a supported display mode. There is also a ":no" command, which is short for ":display normal".

7.1 Options

The display option is associated with a window. It always contains the name of the window's current display mode. You aren't allowed to change the value of this option directly; you must use the ":display mode" command to change the display mode. This option exists solely so that you can write EX scripts which behave differently, depending on the display mode.

The bufdisplay option is associated with a buffer. It should be set to the name of the usual display mode for that buffer. Typically this option will be set from the elvis.arf initialization file, based on the name of the file like this:

	let e=tolower(dirext(filename))
	if knownsyntax(filename)
	then set! bufdisplay=syntax
	else if os=="unix" && buflines >= 1
	then 1s/^#! *[^ ]*\/\([^ ]\+\).*/set! bufdisplay="syntax \1"/x
	if e<<4==".htm"
	then set! bufdisplay=html
	if e==".man" || e==".1"
	then set! bufdisplay=man
	if binary
	then set! bufdisplay=hex

The bufdisplay mode also affects the ^Wd visual command. This command toggles the window between the normal mode and the bufdisplay mode. If bufdisplay is also set to "normal", then ^Wd will toggle between the normal and hex display modes.

7.2 Normal mode

Tab

The tab character is displayed as a variable number of spaces -- however many are needed to move to the next tabstop position.

Newline

The newline character (linefeed) marks the end of a line.

Other control characters

Control characters other than tab and newline are displayed as a caret and a printable ASCII character. For example Control-A is displayed as ^A, and NUL is displayed as ^@. The delete character is displayed as ^?.

Non-ASCII characters

The appearance of non-ASCII characters (i.e., characters 128-255) is controlled by the nonascii option. By default, most non-ASCII characters are assumed to be ordinary printable characters.

7.3 Syntax mode

7.3.1 Options

.---------------------.----------^-------------------------------------.
| OPTION NAMES        | DEFAULT  | AFFECTED TOKEN TYPE                 |
|---------------------|----------^-------------------------------------|
| commentfont, cfont  |  italic  | comments                            |
| stringfont, sfont   |  fixed   | string, character, & regexp literals|
| prepfont, pfont     |emphasized| preprocessor directives             |
| keywordfont, kfont  |   bold   | keywords                            |
| functionfont, ffont |  normal  | identifier followed by function char|
| otherfont, ofont    |   bold   | other special words                 |
| variablefont, vfont |  normal  | variables, fields, etc.             |
^---------------------^----------^-------------------------------------^

Any text that doesn't fall into one of the above groups (punctuation, mostly) is displayed in the normal font. There is no option that controls this; it is hard coded.

You can use the :color command to choose a color for each font, if you wish. Not all user interfaces support color, but the "x11" and "termcap" interfaces do.

7.3.2 Language specification

The "elvis.syn" file is a text file. In it, blank lines and lines which start with a '#' are ignored. Other lines begin with the name of an attribute; the remaining words in the line are values for that attribute. Each language's description begins with an attribute named "language". The following lines (up to the next "language" line or the end of the file) describe that language.

The attributes names are:

language

This word is followed by a whitespace-delimited list of language names. The names are case-sensitive, so you should probably give all names in lowercase so they're easier for the user to type in. The user can indicate which language to use by appending its name to the name of the "syntax" display mode. For example, ":display syntax c++" causes elvis to highlight the text appropriately for C++.

extension

This word is followed by the filename extensions which are commonly used for this language. If the user doesn't specify which language to load, then elvis scans through "elvis.syn" for an extension line which matches the current file name. The extension lines must come immediately after the language line.

NOTE: This is case sensitive! If the file name extension will often be used on case-insensitive file systems (e.g., most Microsoft) then you'll probably want to give both uppercase and lowercase versions of the extension. For example, the description of Microsoft batch file syntax includes "extension .bat .BAT".

keyword

This word is followed by a list of words which should be shown in the keywordfont font. If omitted, then no words are shown in the keywordfont. Long lists can be split into several keyword lines, if you wish. Elvis doesn't care about the order of the words, but the list will be easier to maintain if you keep it alphabetized.

Elvis supports three forms of keywords...

• Most keywords begin with an alphanumeric character or a character in the startword list, and continue with zero or more characters which are alphanumeric or in the inword list.
• The same startword/inword type of keywords can be made somewhat context sensitive by appending a single character which does not appear in the inword. The keyword will only be recognized when it is immediately followed by that character. The HTML syntax highlighting uses this feature to display parameters in a distinctive font.
• Rarely, you may find it convenient to have keywords which consist of one or two punctuation characters, but which don't match the first form of keywords. This is mostly so that Perl's $# variable won't be displayed as a simple dollar sign followed by a comment.

You can list the same keyword in multiple lines (once each in a keyword line, a font line, an anchor line, and a comment line) to specify the various attributes of each keyword. You don't need to list it in a keyword line first; you can introduce new keywords in any of these four line types.

font

This word can be used to cause certain keywords to be displayed in some font other than the keywordfont. The first word after font should be the name of the font (normal, fixed, bold, emphasized, italic, or underlined) or a one-letter abbreviation of a font name. The line's remaining words are keywords which will be displayed in that font.

anchor

This offers a way to restrict certain keywords, so they will only be recognized as such if they occur in a particular column. The first word after "anchor" is a column number -- 1 for the leftmost column, 9 for the first tabstop, and so on. You can also use ^ instead of a number to indicate that the keyword can only appear after whitespace at the front of a line. The remainder of the "anchor" line is the list of keywords which are only special when they occur in that column.

comment

This word is followed by a keyword which marks the beginning of a comment. The comment is assumed to end at the end of the line. Comments are normally shown in the commentfont font, but if you've overridden the keyword's font via a font line in elvis.syn, then the whole comment will be displayed in that font instead. You can define multiple comment keywords, and assign different fonts to them if you wish.

The comment word can also be followed by a pair of one- or two-character sequences which mark the beginning and end of comments which can include newlines. Elvis only supports one multi-line comment style for each language, and it will always be displayed in the commentfont font.

operator

This word is followed by a keyword which the language uses as a prefix for operators, and then by a list of characters which can appear in the operator itself. This affects the ^] visual command for tag searches. As far as I know, the only language that uses this is C++, where it is specified like this:

operator operator ~!%^&*+|-=[]<>/

preprocessor

This word is followed by a single character which, when used at the beginning of a line, marks the start of a preprocessor directive. For C, this is the # character. All preprocessor directives will then be shown in the prepfont font. If omitted, nothing is displayed in the prepfont.

prepquote

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding a file name in a preprocessor directive. For C, this is the < and > characters. The name of the included file will then be displayed using the stringfont font. If omitted, then preprocessor file names will be highlighted as though they were arithmetic expressions.

function

This word is followed by a single character which, if it appears after a word, indicates that the word should be displayed in the functionfont font. For most languages, this will be a ( character. If omitted, nothing is displayed in the functionfont.

startword
inword

These can be followed by a list of punctuation characters which may appear at the start of a word, or in the remainder of the word, respectively. Letters and digits are always legal in words; you don't need to list them.

other

This word indicates which types of words should be displayed in the otherfont font. If omitted, nothing is displayed in the otherfont. It can be any combination of the following symbols:

.-------------.-------------------------------------------------.
| SYMBOL      | HOW TO RECOGNIZE "OTHER" WORDS                  |
|-------------|-------------------------------------------------|
| allcaps     | length >= 2 chars, no lowercase characters      |
| initialcaps | 1st character is uppercase, some are lowercase  |
| initialpunct| 1st character is punctuation, from "startword"  |
| mixedcaps   | 1st character is lowercase, some are uppercase  |
| final_t     | length >= 3 chars, ends with "_t"               |
^-------------^-------------------------------------------------^

string

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding string literals. For C, this is the " character. String literals will then be displayed using the stringfont font. If omitted, then strings will not be recognized.

strnewline

This is followed by backslash, allowed, indent, or empty to indicate how strings can be continued across lines. The default is backslash which indicates a C-style backslash is required to quote the newline characters (which C will then exclude from the string, but elvis doesn't care about that). The other values all indicate that a backslash is not needed, and also give some hints that help elvis detect whether the top of the screen is inside a multi-line string. Specifically, the indent value means that indented lines are rarely a continuation of a string, empty means that empty lines are probably not part of a string, and allowed makes no promises.

The allowed value would be too slow if strings' opening and closing quotes are identical (e.g., if the " character appears at both ends of a string); in this situation, elvis uses empty instead.

Note that the hints are only used for detecting whether the first line starts in a multi-line string. When drawing text after that, elvis treats all non-backslash values identically.

character

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding character literals. For C, this is the ' character. This is shown using the stringfont font, like strings. When parsing, the only difference between the two is that characters can't span lines, but strings can.

regexp

This word is followed by a list of characters which can be used for delimiting a regular expression, which some languages support as a means for specifying strings with metacharacters. (See Section 5 of this manual for a description of elvis' own implementation of regular expressions, which is a typical example.) Regular expressions are displayed using the stringfont font.

Note that regexp accepts a list of characters, while string and character support only a single character. This is because many programming languages allow the programmer to choose from a variety of delimiting characters.

useregexp

The most commonly used delimiter for regular expressions is '/', which many languages also use as the division operator. To avoid mistakenly displaying the division operator as the start of a regular expression, elvis must be sensitive to the context in which it is used. That's what this word is for. The useregexp word is followed by a list of keywords and/or punctuation characters which allow the next character to be recognized as a regular expression. Additionally, regular expressions are allowed at the start of a line.

useregsub

This is used for listing keywords and punctuation characters which may be followed by a regular expression and then substitution text.

ignorecase

This word should be followed by true or false. If true, then elvis won't distinguish between uppercase and lowercase letters when testing whether a word is a keyword (except that in the elvis.syn file, the keywords should be listed in lowercase). If omitted, elvis assumes it should be false.

7.3.3 Example

language java
extension .java .jav
keyword abstract boolean break byte byvalue case cast catch char
keyword class const continue default do double else extends false
keyword final finally float for future generic goto if implements
keyword import inner instanceof int interface long native new null
keyword operator outer package private protected public rest return
keyword short static super switch synchronized this throw throws
keyword transient true try var void volatile while
comment	//
comment /* */
function (
string "
character '
startword _
inword _
other allcaps initialcaps

There is no preprocessor line, because java doesn't use a preprocessor. The "allcaps" and "initialcaps" symbols are given so that constants and class names will be shown in the otherfont.

7.4 Hex mode

One handy feature is the ability to enter characters in hex (either in input mode or as the argument to an r visual command) by typing ^X followed by two hex digits. This feature is always available regardless of the display mode... but this is where is it most useful.

7.5 HTML mode

HTML is a markup language. This means that documents contain a mixture of text and formatting instructions. In HTML there are two types of instructions, called tags and entities. When the document is processed by a program such as Netscape or elvis (in html mode), the tags are stripped out, the entities are converted to a kind of text, and the text is formatted and presented to the user. Ordinarily the user will never see the tags.

Since elvis is primarily an editor, not a viewer, it has two options which allow the tags to become visible: the showmarkups option causes a tag to become visible if the cursor is moved onto it, and the list option makes all tags visible regardless of the cursor position.

There are a lot of good "How To Use HTML" documents on the Net. This is not one of them! I don't intend to do much more than describe the quirks of elvis' implementation of HTML here.

I added HTML support to elvis mostly to support the online help. Consequently, if a feature is hard to implement and the online documentation doesn't use it, then I didn't implement that feature.

If you intend to use elvis as a browser, then I suggest you read the appropriate section in the Tip chapter.

7.5.1 Formatting tags

<html> ... </html>

The entire document should be enclosed in these tags. They don't actually do anything to help format the document, but they may help programs recognize that the document is, in fact, written in HTML.

<head> ... </head>

These should be used to bracket the document's header, if it has one.

<title> ... </title>

These tags are only legal in the document's header. Any text between the <title> and </title> tags will be stored internally as the title of the document. If you print the document, elvis will display the title at the top of each page.

<body> ... </body>

These should be used to bracket the body of the document. They don't actually do anything in elvis, but real Web browsers such as Netscape allow you to specify backgrounds and patterns via BGCOLOR=... and BACKGROUND=... arguments, respectively.

<h1> ... </h1>

These tags bracket the most visible type of section header. Elvis displays <h1> ... </h1> headers in boldface, flush against the left edge of the page. When printing, these headers cause a page break.

<h2> ... </h2>

These bracket the second most visible type of section header. Elvis displays <h2> ... </h2> headers in boldface, indented slightly from the left edge. When printing, these may cause a page break if they would otherwise appear near the bottom of a page.

<h3> ... </h3>

These bracket the third most visible type of section header. Elvis displays them in boldface, indented fully from the left edge so that it lines up with normal text.

<h4>...</h4>
<h5>...</h5>
<h6>...</h6>

These are very minor section headers. Conventional wisdom says that if you're using this many section headers then you would probably do better to split your document into several smaller documents. Elvis displays these headers in an italic font.

<p>

This tag should be placed at the start of each normal paragraph, with the possible exception of the first paragraph after a section header. It causes a blank line to be generated, and any later text to appear starting on a new line.

<br>

This causes any later text to appear starting on a new line. It differs from <p> in that <br> doesn't output a blank line.

<hr>

This outputs a "horizontal rule" -- a line all the way across the page.

<img alt=... src=...>

Elvis can't display graphics, but if it encounters an <img> tag which has an alternate text form (as denoted by an img="text" parameter) then it'll display the alternate text. Otherwise elvis will display "src" URL. Also, if the image isn't already part of a hypertext link, then elvis will treat it as a link to the image's binary data; this offers you a way to fetch images, even though elvis can't display them. The supported URL formats are described in the discussion of the <a> tag, below.

<frame name=... src=...>

Elvis can't display frames either, but it will display the frame's name, and treat that name as a hypertext link to the frame's document. This offers a simple work-around for elvis' lack of real frame support. The supported URL formats are described in the discussion of the <a> tag, below.

<blockquote> ... </blockquote>

This is used to mark a large chunk text which is quoted from another source. Elvis will indent the enclosed text.

<pre> ... </pre>

This brackets text which has already been preformatted by the document's author. Elvis will treat tabs and newlines literally. (Outside of <pre> ... </pre>, they would normally be treated like spaces.) This has been used for presenting tables, poetry, and source code examples.

In fact, elvis has an extension that is useful for tables: If you start with <pre graphic> then elvis will convert certain characters into graphic line-drawing characters. When adjacent to a hyphen character, the hyphen, period, caret are converted into appropriate graphic characters. Additionally, the vertical bar character is always converted to a graphic character. The following was done with a plain <pre>...

.--.--.
|--|--|
|  |  |
^--^--^

... and this was done with <pre graphic>...

.--.--.
|--|--|
|  |  |
^--^--^

<table>...</table>
<tr>...</tr>
<th>...</th>
<td>...</td>

These are used for implementing tables in HTML 3.0. Each table should be enclosed in a <table>...</table> pair. Within the table, each row should be delimited with a <tr>...</tr> pair. Within each row, the information for each column should be enclosed in either a <th>...</th> pair for headers, or a <td>...</td> pair for data.

Elvis doesn't really support these tags very well. Only the bare essentials of these commands have been implemented. They are intended to make tables recognizable as being tables, but not necessarily make them easy to read.

<dir>...</dir>
<xmp>...</xmp>

These are treated almost exactly like <pre> ... </pre>. There are supposed to be some differences, but elvis doesn't support those differences.

<dl> ... </dl>

These are used to bracket a list of definitions. The definitions themselves are marked with the <dt> and <dd> tags, described below.

<dt>

The text after this tag is used as a term to be defined. Elvis displays this text in bold face, indented by the same amount as normal text. This is only legal in a <dl>...</dl> pair.

<dd>

The text after this tag is used as the definition of a term. Elvis displays it in the normal font, indented somewhat more than normal text or the <dt> text. This is only legal in a <dl>...</dl> pair.

<ol> ... </ol>

These are used to enclose an ordered list. The official specifications say that lists may be nested inside one another, but elvis doesn't allow ordered lists to appear inside any other type of list. If a document uses <ol> ... </ol> inside another list, then elvis will act as though <ul> ... </ul> had been used instead. This means that the list items will be marked with bullets instead of numbers. Within the list, <li> tags are used to mark the items.

<ul> ... </ul>

These enclose an unordered list. Each item in the list should be marked with a <li> tag.

<menu> ... </menu>

These enclose an unordered list, like <ul> ... </ul>, but other Web browsers may display <menu> ... </menu> lists in a more compact manner.

<li>

This is used to mark the start of a new item in a list.

<input type=... size=... value=...>
<textarea cols=...>

Elvis can display a mockup of a form, so you can have some idea of how the form would look on a real

<C, this is the < and > characters. The name of the included file will then be displayed using the stringfont font. If omitted, then preprocessor file names will be highlighted as though they were arithmetic expressions.

function

This word is followed by a single character which, if it appears after a word, indicates that the word should be displayed in the functionfont font. For most languages, this will be a ( character. If omitted, nothing is displayed in the functionfont.

startword
inword

These can be followed by a list of punctuation characters which may appear at the start of a word, or in the remainder of the word, respectively. Letters and digits are always legal in words; you don't need to list them.

other

This word indicates which types of words should be displayed in the otherfont font. If omitted, nothing is displayed in the otherfont. It can be any combination of the following symbols:

.-------------.-------------------------------------------------.
| SYMBOL      | HOW TO RECOGNIZE "OTHER" WORDS                  |
|-------------|-------------------------------------------------|
| allcaps     | length >= 2 chars, no lowercase characters      |
| initialcaps | 1st character is uppercase, some are lowercase  |
| initialpunct| 1st character is punctuation, from "startword"  |
| mixedcaps   | 1st character is lowercase, some are uppercase  |
| final_t     | length >= 3 chars, ends with "_t"               |
^-------------^-------------------------------------------------^

string

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding string literals. For C, this is the " character. String literals will then be displayed using the stringfont font. If omitted, then strings will not be recognized.

strnewline

This is followed by backslash, allowed, indent, or empty to indicate how strings can be continued across lines. The default is backslash which indicates a C-style backslash is required to quote the newline characters (which C will then exclude from the string, but elvis doesn't care about that). The other values all indicate that a backslash is not needed, and also give some hints that help elvis detect whether the top of the screen is inside a multi-line string. Specifically, the indent value means that indented lines are rarely a continuation of a string, empty means that empty lines are probably not part of a string, and allowed makes no promises.

The allowed value would be too slow if strings' opening and closing quotes are identical (e.g., if the " character appears at both ends of a string); in this situation, elvis uses empty instead.

Note that the hints are only used for detecting whether the first line starts in a multi-line string. When drawing text after that, elvis treats all non-backslash values identically.

character

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding character literals. For C, this is the ' character. This is shown using the stringfont font, like strings. When parsing, the only difference between the two is that characters can't span lines, but strings can.

regexp

This word is followed by a list of characters which can be used for delimiting a regular expression, which some languages support as a means for specifying strings with metacharacters. (See Section 5 of this manual for a description of elvis' own implementation of regular expressions, which is a typical example.) Regular expressions are displayed using the stringfont font.

Note that regexp accepts a list of characters, while string and character support only a single character. This is because many programming languages allow the programmer to choose from a variety of delimiting characters.

useregexp

The most commonly used delimiter for regular expressions is '/', which many languages also use as the division operator. To avoid mistakenly displaying the division operator as the start of a regular expression, elvis must be sensitive to the context in which it is used. That's what this word is for. The useregexp word is followed by a list of keywords and/or punctuation characters which allow the next character to be recognized as a regular expression. Additionally, regular expressions are allowed at the start of a line.

useregsub

This is used for listing keywords and punctuation characters which may be followed by a regular expression and then substitution text.

ignorecase

This word should be followed by true or false. If true, then elvis won't distinguish between uppercase and lowercase letters when testing whether a word is a keyword (except that in the elvis.syn file, the keywords should be listed in lowercase). If omitted, elvis assumes it should be false.

7.3.3 Example

language java
extension .java .jav
keyword abstract boolean break byte byvalue case cast catch char
keyword class const continue default do double else extends false
keyword final finally float for future generic goto if implements
keyword import inner instanceof int interface long native new null
keyword operator outer package private protected public rest return
keyword short static super switch synchronized this throw throws
keyword transient true try var void volatile while
comment	//
comment /* */
function (
string "
character '
startword _
inword _
other allcaps initialcaps

There is no preprocessor line, because java doesn't use a preprocessor. The "allcaps" and "initialcaps" symbols are given so that constants and class names will be shown in the otherfont.

7.4 Hex mode

One handy feature is the ability to enter characters in hex (either in input mode or as the argument to an r visual command) by typing ^X followed by two hex digits. This feature is always available regardless of the display mode... but this is where is it most useful.

7.5 HTML mode

HTML is a markup language. This means that documents contain a mixture of text and formatting instructions. In HTML there are two types of instructions, called tags and entities. When the document is processed by a program such as Netscape or elvis (in html mode), the tags are stripped out, the entities are converted to a kind of text, and the text is formatted and presented to the user. Ordinarily the user will never see the tags.

Since elvis is primarily an editor, not a viewer, it has two options which allow the tags to become visible: the showmarkups option causes a tag to become visible if the cursor is moved onto it, and the list option makes all tags visible regardless of the cursor position.

There are a lot of good "How To Use HTML" documents on the Net. This is not one of them! I don't intend to do much more than describe the quirks of elvis' implementation of HTML here.

I added HTML support to elvis mostly to support the online help. Consequently, if a feature is hard to implement and the online documentation doesn't use it, then I didn't implement that feature.

If you intend to use elvis as a browser, then I suggest you read the appropriate section in the Tip chapter.

7.5.1 Formatting tags

<html> ... </html>

The entire document should be enclosed in these tags. They don't actually do anything to help format the document, but they may help programs recognize that the document is, in fact, written in HTML.

<head> ... </head>

These should be used to bracket the document's header, if it has one.

<title> ... </title>

These tags are only legal in the document's header. Any text between the <title> and </title> tags will be stored internally as the title of the document. If you print the document, elvis will display the title at the top of each page.

<body> ... </body>

These should be used to bracket the body of the document. They don't actually do anything in elvis, but real Web browsers such as Netscape allow you to specify backgrounds and patterns via BGCOLOR=... and BACKGROUND=... arguments, respectively.

<h1> ... </h1>

These tags bracket the most visible type of section header. Elvis displays <h1> ... </h1> headers in boldface, flush against the left edge of the page. When printing, these headers cause a page break.

<h2> ... </h2>

These bracket the second most visible type of section header. Elvis displays <h2> ... </h2> headers in boldface, indented slightly from the left edge. When printing, these may cause a page break if they would otherwise appear near the bottom of a page.

<h3> ... </h3>

These bracket the third most visible type of section header. Elvis displays them in boldface, indented fully from the left edge so that it lines up with normal text.

<h4>...</h4>
<h5>...</h5>
<h6>...</h6>

These are very minor section headers. Conventional wisdom says that if you're using this many section headers then you would probably do better to split your document into several smaller documents. Elvis displays these headers in an italic font.

<p>

This tag should be placed at the start of each normal paragraph, with the possible exception of the first paragraph after a section header. It causes a blank line to be generated, and any later text to appear starting on a new line.

<br>

This causes any later text to appear starting on a new line. It differs from <p> in that <br> doesn't output a blank line.

<hr>

This outputs a "horizontal rule" -- a line all the way across the page.

<img alt=... src=...>

Elvis can't display graphics, but if it encounters an <img> tag which has an alternate text form (as denoted by an img="text" parameter) then it'll display the alternate text. Otherwise elvis will display "src" URL. Also, if the image isn't already part of a hypertext link, then elvis will treat it as a link to the image's binary data; this offers you a way to fetch images, even though elvis can't display them. The supported URL formats are described in the discussion of the <a> tag, below.

<frame name=... src=...>

Elvis can't display frames either, but it will display the frame's name, and treat that name as a hypertext link to the frame's document. This offers a simple work-around for elvis' lack of real frame support. The supported URL formats are described in the discussion of the <a> tag, below.

<blockquote> ... </blockquote>

This is used to mark a large chunk text which is quoted from another source. Elvis will indent the enclosed text.

<pre> ... </pre>

This brackets text which has already been preformatted by the document's author. Elvis will treat tabs and newlines literally. (Outside of <pre> ... </pre>, they would normally be treated like spaces.) This has been used for presenting tables, poetry, and source code examples.

In fact, elvis has an extension that is useful for tables: If you start with <pre graphic> then elvis will convert certain characters into graphic line-drawing characters. When adjacent to a hyphen character, the hyphen, period, caret are converted into appropriate graphic characters. Additionally, the vertical bar character is always converted to a graphic character. The following was done with a plain <pre>...

.--.--.
|--|--|
|  |  |
^--^--^

... and this was done with <pre graphic>...

.--.--.
|--|--|
|  |  |
^--^--^

<table>...</table>
<tr>...</tr>
<th>...</th>
<td>...</td>

These are used for implementing tables in HTML 3.0. Each table should be enclosed in a <table>...</table> pair. Within the table, each row should be delimited with a <tr>...</tr> pair. Within each row, the information for each column should be enclosed in either a <th>...</th> pair for headers, or a <td>...</td> pair for data.

Elvis doesn't really support these tags very well. Only the bare essentials of these commands have been implemented. They are intended to make tables recognizable as being tables, but not necessarily make them easy to read.

<dir>...</dir>
<xmp>...</xmp>

These are treated almost exactly like <pre> ... </pre>. There are supposed to be some differences, but elvis doesn't support those differences.

<dl> ... </dl>

These are used to bracket a list of definitions. The definitions themselves are marked with the <dt> and <dd> tags, described below.

<dt>

The text after this tag is used as a term to be defined. Elvis displays this text in bold face, indented by the same amount as normal text. This is only legal in a <dl>...</dl> pair.

<dd>

The text after this tag is used as the definition of a term. Elvis displays it in the normal font, indented somewhat more than normal text or the <dt> text. This is only legal in a <dl>...</dl> pair.

<ol> ... </ol>

These are used to enclose an ordered list. The official specifications say that lists may be nested inside one another, but elvis doesn't allow ordered lists to appear inside any other type of list. If a document uses <ol> ... </ol> inside another list, then elvis will act as though <ul> ... </ul> had been used instead. This means that the list items will be marked with bullets instead of numbers. Within the list, <li> tags are used to mark the items.

<ul> ... </ul>

These enclose an unordered list. Each item in the list should be marked with a <li> tag.

<menu> ... </menu>

These enclose an unordered list, like <ul> ... </ul>, but other Web browsers may display <menu> ... </menu> lists in a more compact manner.

<li>

This is used to mark the start of a new item in a list.

<input type=... size=... value=...>
<textarea cols=...>

Elvis can display a mockup of a form, so you can have some idea of how the form would look on a real

<C, this is the < and > characters. The name of the included file will then be displayed using the stringfont font. If omitted, then preprocessor file names will be highlighted as though they were arithmetic expressions.

function

This word is followed by a single character which, if it appears after a word, indicates that the word should be displayed in the functionfont font. For most languages, this will be a ( character. If omitted, nothing is displayed in the functionfont.

startword
inword

These can be followed by a list of punctuation characters which may appear at the start of a word, or in the remainder of the word, respectively. Letters and digits are always legal in words; you don't need to list them.

other

This word indicates which types of words should be displayed in the otherfont font. If omitted, nothing is displayed in the otherfont. It can be any combination of the following symbols:

.-------------.-------------------------------------------------.
| SYMBOL      | HOW TO RECOGNIZE "OTHER" WORDS                  |
|-------------|-------------------------------------------------|
| allcaps     | length >= 2 chars, no lowercase characters      |
| initialcaps | 1st character is uppercase, some are lowercase  |
| initialpunct| 1st character is punctuation, from "startword"  |
| mixedcaps   | 1st character is lowercase, some are uppercase  |
| final_t     | length >= 3 chars, ends with "_t"               |
^-------------^-------------------------------------------------^

string

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding string literals. For C, this is the " character. String literals will then be displayed using the stringfont font. If omitted, then strings will not be recognized.

strnewline

This is followed by backslash, allowed, indent, or empty to indicate how strings can be continued across lines. The default is backslash which indicates a C-style backslash is required to quote the newline characters (which C will then exclude from the string, but elvis doesn't care about that). The other values all indicate that a backslash is not needed, and also give some hints that help elvis detect whether the top of the screen is inside a multi-line string. Specifically, the indent value means that indented lines are rarely a continuation of a string, empty means that empty lines are probably not part of a string, and allowed makes no promises.

The allowed value would be too slow if strings' opening and closing quotes are identical (e.g., if the " character appears at both ends of a string); in this situation, elvis uses empty instead.

Note that the hints are only used for detecting whether the first line starts in a multi-line string. When drawing text after that, elvis treats all non-backslash values identically.

character

This word is followed by a single character, or a pair of single characters, which are used as the quote characters surrounding character literals. For C, this is the ' character. This is shown using the stringfont font, like strings. When parsing, the only difference between the two is that characters can't span lines, but strings can.

regexp

This word is followed by a list of characters which can be used for delimiting a regular expression, which some languages support as a means for specifying strings with metacharacters. (See Section 5 of this manual for a description of elvis' own implementation of regular expressions, which is a typical example.) Regular expressions are displayed using the stringfont font.

Note that regexp accepts a list of characters, while string and character support only a single character. This is because many programming languages allow the programmer to choose from a variety of delimiting characters.

useregexp

The most commonly used delimiter for regular expressions is '/', which many languages also use as the division operator. To avoid mistakenly displaying the division operator as the start of a regular expression, elvis must be sensitive to the context in which it is used. That's what this word is for. The useregexp word is followed by a list of keywords and/or punctuation characters which allow the next character to be recognized as a regular expression. Additionally, regular expressions are allowed at the start of a line.

useregsub

This is used for listing keywords and punctuation characters which may be followed by a regular expression and then substitution text.

ignorecase

This word should be followed by true or false. If true, then elvis won't distinguish between uppercase and lowercase letters when testing whether a word is a keyword (except that in the elvis.syn file, the keywords should be listed in lowercase). If omitted, elvis assumes it should be false.

7.3.3 Example

language java
extension .java .jav
keyword abstract boolean break byte byvalue case cast catch char
keyword class const continue default do double else extends false
keyword final finally float for future generic goto if implements
keyword import inner instanceof int interface long native new null
keyword operator outer package private protected public rest return
keyword short static super switch synchronized this throw throws
keyword transient true try var void volatile while
comment	//
comment /* */
function (
string "
character '
startword _
inword _
other allcaps initialcaps

There is no preprocessor line, because java doesn't use a preprocessor. The "allcaps" and "initialcaps" symbols are given so that constants and class names will be shown in the otherfont.

7.4 Hex mode

One handy feature is the ability to enter characters in hex (either in input mode or as the argument to an r visual command) by typing ^X followed by two hex digits. This feature is always available regardless of the display mode... but this is where is it most useful.

7.5 HTML mode