Difference between revisions of "MrC-temp"

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Caution: Debris Ahead...
 
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<div style="margin-left: 20pt;"><table style="background:#f9f9f9; border-spacing:0px; border-collapse:collapse;">
 
<div style="margin-left: 20pt;"><table style="background:#f9f9f9; border-spacing:0px; border-collapse:collapse;">
<tr><td style="text-align:left; padding-right:20pt">0</td><td>Remove all instances</td></tr>
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<tr><td style="text-align:left; padding-right:20pt"><b>0</b></td><td>Remove all instances</td></tr>
<tr><td style="text-align:left; padding-right:20pt">1</td><td>Remove from the beginning only</td></tr>
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<tr><td style="text-align:left; padding-right:20pt"><b>1</b></td><td>Remove from the beginning only</td></tr>
<tr><td style="text-align:left; padding-right:20pt">2</td><td>Remove from the end only</td></tr>
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<tr><td style="text-align:left; padding-right:20pt"><b>2</b></td><td>Remove from the end only</td></tr>
<tr><td style="text-align:left; padding-right:20pt">3</td><td>Remove from each end</td></tr>
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<tr><td style="text-align:left; padding-right:20pt"><b>3</b></td><td>Remove from each end</td></tr>
 
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! scope="row" style="background: #ecedf3; color: #111; " | Examples
 
! scope="row" style="background: #ecedf3; color: #111; " | Examples
 
|style="background: #f9f9f9; color: #111; " | <span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr)</nowiki></b></span>
 
|style="background: #f9f9f9; color: #111; " | <span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr)</nowiki></b></span>
<div style="margin-left: 20pt;"><p>Removes TT{P}, TT{p}, and TT{r} from "Paper", resulting in "ae".
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<div style="margin-left: 20pt;"><p>Removes <span style="font-family: Consolas, monospace;">P</span>, <span style="font-family: Consolas, monospace;">p</span>, and <span style="font-family: Consolas, monospace;">r</span> from <span style="font-family: Consolas, monospace;">Paper</span>, resulting in <span style="font-family: Consolas, monospace;">ae</span>.
 
The default <i>mode</i> 0 is in effect, removing all instances of the characters specified in the <i>character list</i>.</p></div>
 
The default <i>mode</i> 0 is in effect, removing all instances of the characters specified in the <i>character list</i>.</p></div>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 1)</nowiki></b></span>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 1)</nowiki></b></span>
<div style="margin-left: 20pt;"><p>With <i>mode</i> 1 set, only the inital character TT{P} is removed, resulting in "aper".</p></div>
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<div style="margin-left: 20pt;"><p>With <i>mode</i> 1 set, only the inital character <span style="font-family: Consolas, monospace;">P</span> is removed, resulting in <span style="font-family: Consolas, monospace;">aper</span>.</p></div>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 2)</nowiki></b></span>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 2)</nowiki></b></span>
<div style="margin-left: 20pt;"><p>In <i>mode</i> 2, only one character from the end of the <i>string</i> are removed, leaving "Pape".</p></div>
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<div style="margin-left: 20pt;"><p>In <i>mode</i> 2, only one character from the end of the <i>string</i> are removed, leaving <span style="font-family: Consolas, monospace;">Pape</span>.</p></div>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 3)</nowiki></b></span>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters(Paper, Ppr, 3)</nowiki></b></span>
<div style="margin-left: 20pt;"><p>Both the front and back are affected in <i>mode</i> 3, causing the removal of the leading TT{P} and trailing TT{r} resulting in "ape".</p></div>
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<div style="margin-left: 20pt;"><p>Both the front and back are affected in <i>mode</i> 3, causing the removal of the leading <span style="font-family: Consolas, monospace;">P</span> and trailing <span style="font-family: Consolas, monospace;">r</span> resulting in <span style="font-family: Consolas, monospace;">ape</span>.</p></div>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters([artist], /(/))</nowiki></b></span>
 
<span style="font-family: Consolas, monospace;"><b><nowiki>removecharacters([artist], /(/))</nowiki></b></span>
 
<div style="margin-left: 20pt;"><p>Removes any opening or closing parenthesis from anywhere within the [artist] field.</p></div>
 
<div style="margin-left: 20pt;"><p>Removes any opening or closing parenthesis from anywhere within the [artist] field.</p></div>
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<div style="text-align:right;">([[#top|Back to top)]]</div>
 
<div style="text-align:right;">([[#top|Back to top)]]</div>
  
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[1 mikeimac:expr-lang] $
 
   
 
   
 
... and more to come...
 
... and more to come...

Revision as of 22:36, 16 August 2013

Note: The Smartlist and Search - Rules and Modifiers page is now at its permanent home: Smartlist and Search - Rules and Modifiers

Note: The Regex() page is now at its permanent home: MC expression language page

Note: The File Properties page is now at its permanent home: File Properties (tags) page

Contents

This is MrC's working space for work-in-progress Wiki pages.

Caution: Debris Ahead...


Functions

Conditional Functions

The functions in this section test one or more arguments to produce either a true or false outcome, and execute specific actions depending upon that result.

Although the expression language does not directly support AND, OR, and XOR, these can be easily emulated. See: Database_Expressions_AND_OR_And_XOR.

The NOT operator ! (exclamation point) may be used in a conditional to invert the sense of the conditional test. Inverting the sense of a test can make reading expressions easier, or support better IfElse() sequences.

If(…): Conditional if-else evaluator

If() if(test expression, true expression, false expression)

The If() function is used to evaluate a test expression, and will output the result of the true expression or false expression, depending upon the evaluation result. The test expression is expected to return a 0 (false value) or a non-zero (true value). Nesting is allowed. If the test expression is preceded by the NOT operator (!, an exclamation point), the sense of the test is inverted. Non-zero values are inverted to 0, and 0 is inverted to 1.

Examples if(isequal([artist], bob dylan, 1), Genius, Mediocre)

Outputs "Genius" when artist is Bob Dylan and "Mediocre" otherwise.

if(isequal([artist], bob dylan, 1), Genius, if(isequal([album], Joshua Tree, 8), Great Album, Mediocre))

This nested If() expression expands on the previous example, by first evaluating if the artist is Bob Dylan, and outputs "Genius" if true. When the artist is not Bob Dylan, the album is then tested to see if it is "Joshua Tree", and if so outputs "Great Album", otherwise outputs "Mediocre".

if(!isempty([comment]), regex([comment], /#^(\\S+\\s+\\S+\\s+\\S+)#/, 1), *No Comment)

Output's the first three words of the comment field; otherwise, outputs *No Comment. By using the NOT operator, the sense of the conditional is inverted so that the more interesting case is moved ahead of the more mundane case.

IfElse(…): Conditional if-elseif evaluator

IfElse() ifelse(test1, action1, test2, action2, test3, action3, )

The IfElse() conditional provides a convenient mechanism for shortening and more clearly expressing nested conditionals into an alternating sequence of tests and actions. One or more test/action pairs may be specified.

For example, consider a nested sequence of If() tests such as the following pseudo-code:

if (test1)
action1
else if (test2)
action2
else if (test3)
action3

The IfElse() statement may be used to more cleanly express the flow of expression by removing the superfluous internal If() statements, converting the clumsy expression:

if(test1, action1, if(test2, action2, if(test3, action3)))

into the more elegant:

ifelse(test1, action1, test2, action2, test3, action3)

If any of the test expressions test1, etc. are preceded by the NOT operator (!, an exclamation point), the sense of that test is inverted. Non-zero values are inverted to 0, and 0 is inverted to 1.

Examples ifelse(isequal([media type], Audio), Le Tunes, isequal([media type], Video]), Flix)

If media type is audio, outputs "Le Tunes", else if media type is video, outputs "Flix"

ifelse(isequal([artist], Bob Dylan), Genius, isequal([album], Joshua Tree, 8), Great Album, 1, Mediocre)

This example, implements the nested if statements from the If() section above, first testing if the artist is Bob Dylan, and if true, outputs "Genius", otherwise evaluates the second test to determine if the album is "Joshua Tree", and if true, outputs "Great Album", otherwise, performs a final test, in this case a degenerate test of 1 (and 1 is always true), thus outputting the value "Mediocre".

Test and Comparison Functions

The functions in this section return a Boolean value of either 1 (true) or 0 (false). They are generally used to drive an action specified in one of the Conditional Functions.

Compare(…): Compares two numbers

Compare() compare(value1, operator, value2)

The Compare() function compares two numeric values value1 and value2 using the specified operator.

Available operator values:

=Equivalence
<Less than
<=Less than or equal to
>Greater than
>=Greater than or equal to

Outputs 1 if the comparison is true, and 0 otherwise.

Examples compare([bitrate], <, 320)

Returns 1 when the bitrate is less than 320 (Kbps), and 0 otherwise.

if(compare(math(now() - [date modified, 0]), >, 21), Expired, formatdate([date modified, 0], elapsed))

Outputs the age of files under 21 days old, or 'Expired' for older files.

IsEqual(…): Compares two values in one of nine specified modes

IsEqual() isequal(value1, value2, mode)

The IsEqual() function compares value1 with value2 using any mode from the list of modes below. Outputs 1 when the comparison succeeds according to the mode, and 0 otherwise. Although the mode is specified as the last argument, the comparison should be mentally read as: value1 mode value2.

Available mode values:

0Case-sensitive string compare for equality
1Case-insensitive string compare for equality
2Numeric compare for equality
3Numeric less than
4Numeric less than or equal to
5Numeric greater than
6Numeric greater than or equal to
7Substring search (case sensitive)
8Substring search (case insensitive)

Argument mode is optional (defaults to 0).

Examples isequal([artist], [album], 1)

If the artist and album values are the same, the output will be 1, otherwise, the output will be 0.

if(isequal([artist], [album], 1), Eponymous, [album])

The If() function basis its decision on the outcome of IsEqual(), so if the artist and album values are the same, the output will be Eponymous, otherwise, the output will be the value of album.

if(isequal([artist], [album], 1), Eponymous/,, [album]/))

This example demonstrates the character 'escaping' mentioned in the overview earlier.

Here, we want the output to be either "Eponymous," (note the inclusion of the comma) or the album value with a closing parenthesis. In order to achieve this, the comma, and the closing parenthesis, are escaped using a forward-slash character.

This informs the expression evaluator that these characters are not part of the expression syntax and are to be treated literally.

if(isequal([filename (path)], classical, 8), Classical, Not Classical)

Because compare mode 8 has been specified, if the word "classical" appears anywhere in the case-insensitive file path, the expression will return Classical, and if not it will return Not Classical.

IsEmpty(…): Tests a value for emptiness

IsEmpty() isempty(value, mode)

The IsEmpty() function tests the given value for emptiness. The value passed is typically an Media Center field, so that some action may be taken when the field is or is not empty. Returns 1 when the value is empty, otherwise 0.

Available mode values:

0String test (field must be empty to get a positive result)
1Numerical test (field must be empty, or contain 0 to get a positive result)

Note that Media Center does not discriminate between a 0 value and an empty value for fields of type Integer and Decimal - both 0 and empty are considered equivalent for these field types. This is useful for fields such as the integer field Disc #, where an empty or 0 value implies that Disc # contains no useful data, and should be generally ignored or absent in display output.

Pay particular attention to the third example offered below, as it covers a caveat that comes with this particular function.

Argument mode is optional (defaults to 0).

Examples isempty([comment], 0)

If the comment field is empty, IsEmpty() returns 1, otherwise 0.

isempty([track #], 1)

Performs a numerical test for data in the [track #] field. If the field is empty or 0, a 1 is returned, otherwise 0 is returned.

ifelse(!isempty([disc #]), [disc #])

Outputs the value of the disc # field when it is not empty.

IsRange(…): Tests a value for inclusion within a given range

IsRange() isrange(value, range)

The IsRange() function tests if a value falls within a given range of values. If the value falls within the given range, 1 is returned, otherwise 0 is returned.

A range is specified in the form of low-high, where low and high are either letters or numbers. The lowest value comes first, the highest second. Both low and high must be the same kind (letters or numbers). The low and high values are inclusive.

Example Ranges:

1-100
a-z
c-d
23-7542
Examples isrange([artist], a-c)

Artist values of Abba or Blondie will result in a 1, but ZZ Top will return a 0.

if(isrange([bitrate], 96-191), Poor Quality, High Quality)

Returns Poor Quality for any file whose bitrate falls in the range of 96 to 191, and returns "High Quality" for all bitrates.

Additional Examples

Using IsRange() in a Search List.

IsMissing(…): Tests to see if a file exists on the system

IsMissing() ismissing(filepath)

The IsMissing() function tests for the existence of a file in the file system. If the file is missing, the function returns 1, otherwise 0 is returned if the file exists. This function is useful for checking for missing files in a Library. IsMissing() treats special entries such as ripped Blu-ray or DVDs as single files, even though they physically exist in the file system as several files and directories.

Note: Any view or list that uses IsMissing() will be slow, is Media Center must interogate each referenced file in the file system. The larger the number of files being queried, the longer it will take to produce results. Use IsMissing() with care.

Argument filepath is optional (defaults to [Filename]).

Examples ismissing()

If the referenced file was not found in the file system, 1 is returned; othewise 0 is returned.

ismissing(C:\Music\My Lost File.mp3)

Checks for "My Lost File.mp3" and returns 1 (positive) if the file does not exist, and 0 (negative) if the file does exist.

if(ismissing(), File is missing, File exists)

Outputs "File is missing" or "File Exists" depending on the result returned by IsMissing().

[=ismissing([filename])]=1

This example demonstrates how to construct an expression for use as a Media Center search query. If you place this in the search field in the top right corner of the program while viewing all of your library, it will filter the list, leaving only the missing files on view. If all files in library exist, this list will be empty. You could also create a view scheme and use this string in the "Set rules for file display" search to give you a view that you can visit periodically to check that your library is not missing any files.

IsRemovable(…): Tests to see if a file is stored on removable media

IsRemovable() isremovable(filepath)

The IsRemovable() function tests if a file resides on removable media and if so, returns 1, and if not, returns 0. The Media Center field [Removable] also provides the same value for a given file.

Argument filepath is optional (defaults to [Filename]).

Examples isremovable()

Checks if the current file is on removable storage, and if so, returns 1, otherwise returns 0.

IsInPlayingNow(…): Tests to see if a file is in the Playing Now playlist

IsInPlayingNow() isinplayingnow(filepath)

The IsInPlayingNow() function tests if a file is in any zone's Playing Now list. Used as an expression category, pane or file list column allows distinguishing files that are in the Playing Now list.

Argument filepath is optional (defaults to [Filename]).

Examples isinplayingnow()

If the file in the Playing Now list, returns 1, otherwise returns 0.

if(isinplayingnow(), Queued, Not queued)

If the file in the Playing Now list, returns Queued, otherwise Not queued.

Additional Examples

How to use IsPlaying() and IsInPlayingNow()

IsPlaying(…): Tests to see if a file is in currently being played

IsPlaying() isplaying(filepath)

The IsPlaying() function tests if a file is playing in any zone. Used as an expression category, pane or file list column allows distinguishing files that are playing now.

Argument filepath is optional (defaults to [Filename]).

Examples IfElse(IsPlaying(), <font color="ff0000">♪<//font>, IsInPlayingNow(), ♪)

This expression in a file list expression column shows which files are in the Playing Now list and which are currently playing by outputing a musical note in the column. The musical note will be displayed in red for any currently playing file.

Additional Examples

How to use IsPlaying() and IsInPlayingNow()
How to play an artist's full work when a genre is shuffling?

Formatting Functions

The functions in this section format their arguments in specific ways. Some functions are used for formatting values for better presentation, or according to some format, while other functions work on Media Center internal "raw" data to convert to user-friendly formats.

Certain Media Center fields are used to store values in ways that are internally convenient or effecient. But these field values are not terribly useful or meaningful when used directly.

For example, the Duration field holds values as a number seconds of length, while various Date/Time fields such as Date or Last Played store values as floating point numbers specifying a number of days and fractions of a day since a particular epoch time.

Media Center will generally format fields using the "display" format where necessary, such as in panes, file list columns, or various tools such as the Rename, Move & Copy tool. When a function requires a raw field value, or you want to access a raw field value, by sure to use the raw field format. This is done by appending a ,0 to the field's name inside the brackets. Example: [Date Imported,0].

Delimit(…): Outputs a value with head/tail strings when value is non-empty

Delimit() delimit(expression, tail, head)

The Delimit() function outputs the value of expression prepended with a head string and/or appended with a tail string, but only if the value of the expression is non-empty. Nothing is output when the expression evaluates to empty.

Argument tail is optional (defaults to SPACE).

Argument head is optional (defaults to EMPTY).

Examples delimit([Track #], .)

Appends a period after a track number if [Track #] is not empty, such as "12.".

delimit([Date (year)], {, })

Outputs the year surrounded by curly braces, for example "{2012}".

FormatBoolean(…): Formats a boolean (true / false) value in a specified manner

FormatBoolean() formatboolean(conditional, true string, false string)

The FormatBoolean() function outputs true string and false string values to represent the 0 or 1 Boolean output resulting from the conditional expression. When the conditional evalutes to 1, the true string will be output, otherwise the false string will be output.

Argument true string is optional (defaults to True).

Argument false string is optional (defaults to False).

Examples formatboolean(isempty([number plays]), Never Played, Has Been Played)

Returns "Never Played" when the expression IsEmpty() evaluates to 0, and "Has Been Played" when it evaluates to 1.

formatboolean(math([track #] % 2)

Outputs the default True label for odd track numbers, and the default False label for even ones.

FormatDuration(…): Presents a duration of seconds in a reader friendly format

FormatDuration() formatduration(duration value)

The FormatDuration() function formats a duration value into a friendly format. The duration value argument is expected to be a value representing a number of seconds, typically used for media file duration. Media Center internally stores duration values in seconds.

Examples formatduration([duration,0])

Outputs a friendly display of the duration field. This is the same output shown using the Duration field in a file list.

formatduration(600)

This will output ten minutes in the format 10:00.

FormatFileSize(…): Presents a number of bytes in a reader friendly format

FormatFileSize() formatfilesize(bytes value)

The FormatFileSize() function formats a bytes value into a friendly format. The bytes value argument is expected to be a value representing a number of bytes, typically used for media file size. Media Center internally stores file size values in bytes. FormatFileSize() will convert those byte values into unitized friendly formats such as 50 bytes, 3.2 KB or 10.4 MB.

Examples formatfilesize([file size,0])

Outputs a friendly format of the file size field. This is the same output shown using the File Size field in a file list.

formatfilesize(56123456)

Outputs the bytes value 56,123,456 as 53.5 MB.

FormatNumber(…): Formats and rounds a number to a specified number of decimal places

FormatNumber() formatnumber(value, decimal places, label zero, label plural, label singular)

The FormatNumber() function formats a numeric value to a specified number of decimal places, rounding its value, and optionally outputs value-dependent labels, which can be used to construct more gramatically-correct output. The value can be any numeric value. The decimal places argument specifies the number of digits to be used after the decimal point. Use -1 to output as many decimal places as available.

The label selected depends on the original value, not the resulting formatted value.

The label zero argument is output instead of a formatted value when the original value is 0. When this label is specified as empty, label plural is used. The label plural argument is appended to the formatted value when the original value is more than 1. The label singular argument is appended to the formatted value when the original value is equal to 1.

Note: FormatNumber() will not output additional zero's after the decimal point. In otherwords, FormatNumber() rounds fractional values, but does not zero fill.

Argument decimal places is optional (defaults to 0).

Argument label zero is optional (defaults to label plural).

Argument label plural is optional (defaults to 0).

Argument label singular is optional.

Examples formatnumber([duration,0], 2)

Returns a file's duration (which are in seconds) rounding to two decimal places.

formatnumber([number plays,0], 0, Unplayed, Plays, Play)

Outputs values in whole number formats (no decimals shown). When the number of plays is 0, the output will be "Unplayed".

When it is more than one, such as six, outputs "6 Plays".

And when the number of plays is one, outputs "1 Play".

formatnumber([number plays,0], 0, , Plays, Play)

Same as the previous example, but uses the default value for label zero (which is label plural), so that when number of plays is zero, output is "0 Plays".

formatnumber([number plays,0], , , , Time)

In this example, only label singular argument is specified (as "Time"), so all other arguments use their defaults values. The output will be "0" when number of plays is zero, "1 Time" when number of plays is one, and the actual number of plays for other values (e.g. "6").

FormatRange(…): Formats a value as a range

FormatRange() formatrange(value, range size, mode)

The FormatRange() function creates numerical or alphabetic groupings of size range size, and returns the grouping where value falls. Only the first character of value is considered and used. The range size is a numerical value specifying how wide the range should be. Numeric ranges are 0-based. The mode specifies the type of range grouping.

Available mode values:

0Automatically choose between number / letter grouping
1Letter grouping
2Number grouping

Argument range size is optional (defaults to 1).

Argument mode is optional (defaults to 0).

Examples formatrange([artist], 3, 1)

Outputs the range that the artist's first letter falls within. With a range size of 3 and using mode 1 (letter grouping), ranges will produced in the form of a-c, d-f, g-i, ...

formatrange([artist])

With range size and mode values left unspecified, default values are used, so automatic range groupings of size 1 are output. Hence, the first character of [artist] will be output.

formatrange([bitrate], 100, 2)

Numeric range groupings of size 100 will be output, for the value of [bitrate]. Possible outputs are: 0-99, 100-199, 200-299, ...

Additional Examples

How to produce 1-based range values.

Orientation(…): Outputs the orientation of an image

Orientation() orientation()

The Orientation() function outputs one of the following words indicating the orientation of an image file:

PortraitWhen height > width
LandscapeWhen width > height
PortraitWhen height = width
Examples if(isequal(orientation(), Square), Square, Rectangle)

Outputs "Square" for square images or "Rectangle" for portrait and landscape images.

PadNumber(…): Adds leading zeros to any given number

PadNumber() padnumber(value, number digits)

The PadNumber() function adds leading zeros to any given number value, producing a value of length number digits.

Examples padnumber([track #], 2)

This will pad the track number with leading zeros sufficient to ensure the output is minimally two digits in length.

padnumber(counter(), 4)

Outputs 4 digits of zero-padded numbers produced by Counter(). For example, 0001, 0002, 0003, ...

RatingStars(…): Outputs the value of Rating as a number of star characters

RatingStars() ratingstars()

The RatingStars() function outputs the Rating field's value as the equivalent number of black star characters.

Examples ratingstars()

For a file that has a Rating of 4, outputs ★★★★.

Watched(…): Outputs a formatted video bookmark

Watched() watched(mode)

Outputs a video's bookmark position in a human-readable format, using a specified mode.

Available mode values:

0Output a human-readable watched status.
1Output a numeric watched value, 0 if not watched, 1 if partially watched, 2 if entirely watched.
2Output a watched checkmark ✓ if watched

Argument mode is optional (defaults to 0).

Examples watched()

Outputs formatted watched status, such as "57% on Sep 25", or "Aug 21", or nothing when the video has not been watched.

String Manipulation

The functions in this section are used primarly to manipulate strings. Since the Media Center expression language is primarly string-oriented, these functions provide a means to manipulate field values or the output from other expressions.

Clean(…): Clean a string to be used for various operations

Clean() clean(string, mode)

The Clean() function is generally used to sanitize a string by stripping empty brackets, remove superfluous dash characters, eliminate leading or trailing articles, or replace filesystem-illegal characters. It is typically employed before some operation such as Rename to clean the product of joining various fields, some of which may be empty, or to produce filesystem-safe filenames. It may be used for a variety of purposes, however.

Available mode values:

0Removes empty () and [], superfluous dash (-) and whitespace characters and sometimes comma (be careful)
1Removes the article 'the' from the beginning and ', the' from the end
2Removes any article (a, an, the, etc.) from the beginning and end
3Replaces each filesystem-illegal character \ / : * ? " < > | with an underscore _, and replaces each unprintable character with a space

Argument mode is optional (defaults to 0).

Examples clean([album] - [date])

The concatenation of [Album] - [Date] may leave a dangling " - " string when date is empty. Clean() in the default mode removes this dangling string.

clean(The Beatles, 1)

For sorting or grouping purposes, it is often desirable to remove the leading article "The" from a string. Clean() in mode 1 provides a convenient solution, and in this example produces "Beatles".

clean(AC//DC: Back In Black, 3)

When an expression is to be used to produce a filename, filesystem-illegal characters must be removed or converted to legal characters. Clean() in mode 3 will convert such characters into safe underscores. This example would produce the filesystem-safe value of "AC_DC_ Back In Black".

clean(\//:*?"<>|, 3)

This trivial example demonstrates how all filesystem-illegal characters are converted to underscores, producing the nine-character output "_________" which consists entirely of underscores.

FixCase(…): Changes the case of a given string

FixCase() fixcase(string, mode)

The FixCase() function will convert the supplied text string according to the specified mode.

Available mode values:

0Title Case
1All Words
2First Word
3All Uppercase
4All Lowercase

Argument mode is optional (defaults to 0).

Examples fixcase(enjoy the silence)

The default mode 0 is used, so the output is "Enjoy the Silence".

fixcase(enjoy the silence, 1)

Using mode 1, all words are uppercased, so the output is "Enjoy The Silence".

fixcase(MY ALbUm IS cAlLeD: adam, 4)

Outputs "my album is called: adam".

FixSpacing(…): Intelligently splits adjacent camel-cased words

FixSpacing() fixspacing(string, mode)

The FixSpacing() function inserts spaces between adjacent camel-cased words in string. It is useful for helping to clean and convert metadata that favors compactness over standard sentence structure.

Available mode values:

0Disables conversion
1Enables camel-case conversion

Argument mode is optional (defaults to 1).

Examples fixspacing(OneWorld)

Outputs "One World".

fixspacing([name], 1)

Outputs the name field with any camel-case converted into standard sentence structure. If the value of name was, "MiracleOn34thStreet", the output would be "Miracle On 34th Street".

fixspacing(Another [name])

Assuming the same [name] as above, this would return "Another Miracle On 34th Street".

Hexify(…): Hexifies a string to make it suitable for web usage

Hexify() hexify(string)

The Hexify() function URI encodes a string to make it useable by a browser or search engine. Hexify() is typically used by expressions generating or working on URLs in Media Center's Link Manager.

Examples hexify(Oasis - /(What's The Story/) Morning Glory?)

The result is "Oasis%20-%20%28What%27s%20The%20Story%29%20Morning%20Glory%3F".

Left(…): Retrieves a specified number of characters from the left of a string

Left() left(string, quantity)

The Left() function retrieves no more than quantity characters from the left of the string.

Examples left([filename], 3)

Return the Windows drive letter, colon and first back-slash from the filename.

Length(…): Returns the number of characters in a string

Length() length(string)

The Length() function returns the number of characters contained in string.

Examples length(A Simple Plan)

Returns 13.

if(compare(length([filename]), >=, 68), Long, Short)

The length of the filename is calculated, and compared against 68, outputting "Long" when the length is greater than or equal to 68, and "Short" otherwise.

Mid(…): Retrieves specified characters from a string

Mid() mid(string, start position, quantity)

The Mid() function returns a specified quantity of characters from the start postion in string.

The start postion is 0-based (i.e. the first character is considered position 0). A quantify of -1 returns all characters from the start postion to the end of string.

Argument start position is optional (defaults to 0).

Argument quantity is optional (defaults to 1).

Examples mid(12345)

Returns "1", using is the default quantity (1) of characters from the default start position of (0 - the beginning of the string).

mid(12345, 1, 2)

Returns 2 characters begining at start position 1, which is "23".

Additional Examples

An example that uses Mid() to re-order a date field.
An example that uses Mid() to output a number of stars based on an arbitrary rating value.

Regex(…): Regular expression pattern matching and capture

Regex() regex(string, regexp, run mode, case sensitivity)

This function performs regular expression (RE) pattern matching on a string. The string is evaluated against the regular expression regexp, and run mode dictates the values output by Regex(). The three modes allow for match testing, capture output, or silent operation.

All match captures are placed into special variables referenced as [R1], [R2], ... [R9], which can be used in later in the expression. The contents of the captures [R1] ... [R9] are available until the end of the expression, or Regex() is run again, whereby they are replaced. The regular expression implementation used prior to Media Cener 19 is the Microsoft 2010 TR1 engine, and in Media Cener 19 it is the Boost engine.

Available run mode values:

0Runs in Boolean test mode, returning either a 1 or 0, indicating whether the string matched (1) or did not match (0) the regexp. This run mode is useful within an If() test, so that different true or false actions may be taken.
1 to 9Outputs the specified Nth capture group's contents, where N ranges from 1 to 9. Only a single capture is output in this mode, but all captures are available in the [R1] ... [R9] capture variables. This run mode is used to easily output a single matching sub-string.
-1Runs in silent mode, with no output being produced. This run mode is useful as a means to capture portions of the string to be later used in subsequent portions of an expression.

The case sensitivity argument toggles the case-sensitivity of regular expression matching. Note that case insensitivity does not apply to characters inside a character class [ ]. Use both uppercase and lowercase characters when necessary to match either case (e.g. [aAbB] to match either uppercase or lowercase A or B).

Available case sensitivity values:

0Ignore case when matching (e.g. the letters E and e are identical)
1Consider case when matching (e.g. the letters E and e are considered different)

The regular expression language assigns special meaning to many characters. A few of these meta-characters, such as forward slash /, comma , and both ( and ) are also reserved and used by the Media Center expression language. To force the Media Center expression engine to ignore the meta-characters in regexp, surround the entire regular expression with /# #/. This is one of Media Center's escapements, which tells the expression engine to ignore everything inside, so that the entire, uninterpreted regexp can be provided to the Regex() regular expression evaluator. Although surrounding regexp by /# #/ is not necessary or required when no conflicting characters are in use, and you may manually escape the expression languages meta-characters with a forward slash /, it is probably a safe practice to always encase every regexp within /# #/.

Argument run mode is optional (defaults to 0).

Argument case sensitivity is optional (defaults to 0).

Examples ifelse(regex([name], /#^(the|an|a)\b#/, 0, 1), Fix your case!)

Searches the name field for any of the lowercse articles "the", "and" and "a" at the beginning of name, and outputs "Fix your case!" when the match succeeds. The run mode is 0 which is a test and capture mode, and case sensitivity is enabled.

if(regex([artist], /#([[:punct:]])#/, 0), [R1] --> [Artist], No Punctuation)

Using the default mode 0, Regex() will output a Boolean for use inside a condtional to cause some action to occur based on the match success or failure.

This example matches against the artist field looking for any punctuation character.

If the match succeeds (a punctuation character was found), that character is output followed by the string " --> " and the artist. In there was no match, the string "No Punctuation" is output.

regex(D03T02 some track.mp3, /#^D(\d+)T(\d+)#/, 1)Disc: [R1], Track: [R2]

The string is matched against the regexp that is looking for a D followed by any number of digits, followed by a T and then more digits. Those digits were captured, and later used to output the value "Disc: 03, Track: 02".

regex([filename (name)], /#^(\d+)-#/, -1)Track number is [R1]

Using run mode -1, the file's name is pattern tested against the regexp which is looking for leading digits followed by a dash. Those digits are captured in buffer [R1] which is used later in the expression. If the file name was "2-foo.mp3", the output would be "Track number is 2".

regex([filename], /#(\d{1,2})\.(\d{1,2}).(\d{4})#/, -1)[R3]//[R1]//[R2]

Matches and captures a date formatted as dd.mm.yyyy anywhere within the filename, and rearranges it in a standard format of yyyy/mm/dd.

Since run mode is -1, no output occurs. However, captured match segments are made available for subsequent use.

The three captures, [R1], [R2] and [R3] are arranged in the textual output so that we get the desired year/month/day ordering, such as 2011/08/19.

RemoveCharacters(…): Removes specified characters from a string

RemoveCharacters() removecharacters(string, character list, mode)

This function will remove from string any characters in the character list. The characters removed depend upon the mode specified. The function operates in a case-sensitive manner.

Available mode values:

0Remove all instances
1Remove from the beginning only
2Remove from the end only
3Remove from each end

Argument mode is optional (defaults to 0).

Examples removecharacters(Paper, Ppr)

Removes P, p, and r from Paper, resulting in ae. The default mode 0 is in effect, removing all instances of the characters specified in the character list.

removecharacters(Paper, Ppr, 1)

With mode 1 set, only the inital character P is removed, resulting in aper.

removecharacters(Paper, Ppr, 2)

In mode 2, only one character from the end of the string are removed, leaving Pape.

removecharacters(Paper, Ppr, 3)

Both the front and back are affected in mode 3, causing the removal of the leading P and trailing r resulting in ape.

removecharacters([artist], /(/))

Removes any opening or closing parenthesis from anywhere within the [artist] field.

[1 mikeimac:expr-lang] $

... and more to come...