TweetFollow Us on Twitter

September 96 - MPW TIPS AND TRICKS: Automated Editing With StreamEdit

MPW Tips and Tricks: Automated Editing With StreamEdit

Tim Maroney

In this column in Issue 26 of develop, I showed you a wide range of scriptable editing commands available from the MPW Shell. This time I'll discuss a single tool that provides a powerful self-contained text-editing scripting language, StreamEdit.

Why would you want to use StreamEdit instead of the other text-editing features of the MPW Shell?

  • Performance -- A StreamEdit script is faster than an MPW script containing various Replace and Find commands.

  • Self-containment -- Because StreamEdit is a self-contained tool, you can run it from within ToolServer, unlike the scriptable editing commands discussed in Issue 26, which are available only in the MPW Shell itself. This means you can use StreamEdit to create lightweight drag-and-drop grinder AppleScript scripts that send StreamEdit commands to ToolServer.

  • Consistency -- Keeping all your editing in a single scripting language confers the elusive mystical boon of code consistency, making your system easier to maintain and modify in the future.


GETTING TO KNOW YOU

StreamEdit is based very closely on the hoary UNIX tool named sed. If you already know sed, much of this will be familiar, but StreamEdit isn't directly compatible with sed scripts. StreamEdit implements a pattern-matching language. Every time a particular pattern is matched, a sequence of commands will be executed. As in most pattern-matching languages, StreamEdit's scripts are lists of pattern/command pairs, with the pattern coming before the command. The input file or files are read through the script interpreter, which searches for instances of the patterns and executes the corresponding commands. Anything that doesn't match a pattern is passed through unchanged.

StreamEdit scans one line at a time through the input, matching its current line to every pattern in its script. After processing each line, it writes out the modified line. The result is a concatenation of three internal buffers: the insert buffer, then the edit buffer, and finally the append buffer. The edit buffer gets filled with the current line, while the other buffers are empty at the start. The Insert and Append commands place text in the insert and append buffers, allowing you to add text to the beginning and end of the output line. The Change, Delete, and Replace commands modify the contents of the edit buffer.


SHARING ADDRESSES

As usual, MPW uses words in ways previously unknown in human speech. In StreamEdit, patterns are referred to as "addresses." There are two kinds of addresses: line numbers and regular expressions. Line numbers ought to be self-explanatory, but it may help to note that the numbers must be Arabic numerals rather than Roman, and must be in base 10 rather than the hexadecimal or sexagesimal number systems. There are three special line numbers:
  • the bullet symbol (Option-8), meaning the point before the first line (enabling you to add a line before the first line, for example)

  • the infinity symbol ([[infinity]], Option-5), meaning the point after the last line

  • dollar sign ($), meaning the last line
    The keyboard shortcuts, as always in this column, are for American QWERTY keyboards; if you've got some other type of keyboard, you're on your own.
Regular expressions are expressions that manage their diets sensibly. They can be used for searching, and were explained in detail in Issue 26. In StreamEdit addresses, though, regular expressions find the entire line containing the pattern, rather than just the pattern. Regular expressions are denoted by slashes. Only forward slashes are used (StreamEdit doesn't have a backward search mode, having been frightened at an early age by the legends of Eurydice and Lot's wife). Three new constructs have been added to regular expressions in StreamEdit:
  • ç (Option-C), which indicates a case-sensitive search

  • // (two slashes), which means the last regular expression that was matched

  • <=variable>= (a variable name embedded in inequality operators, here overloaded as a special kind of angle brackets, and typed as Option-comma and Option-period), which means the text of an expanded StreamEdit variable, treated as literal text to be matched rather than as a regular expression
StreamEdit has variables that can be set with the Set command (more on this later) or from the command line using the -set variable [=value] option.

You can form more complex addresses using a few operators. The Boolean and, or, and not operators are the same as in C (&&, ||, and !, respectively). Parentheses can be used for grouping within addresses. The comma operator matches the range of lines specified; for example, 3,5 matches lines 3 through 5. A range address matches each of the lines in the range, if any. It can be thought of as matching more than once: it fires off the accompanying command on the first line matched, the last one matched, and all lines in between. If the termination condition is never met, the address continues to match until the end of input. This could happen if you specify a range of lines ending at line 15, for instance, and there are only ten lines in the file, or if your range termination condition is a regular expression that doesn't appear anywhere in the input.


TAKING ACTION

Matching patterns is very nice, but what do you do once you match them? Statements in StreamEdit attach actions to patterns. An action consists of one or more commands, separated by semicolons or by the end of a line. There's no begin or end bracketing as in Pascal or C. Addresses and commands are syntactically distinct, so the script interpreter can figure out where the list of commands for a pattern ends and the next pattern begins.

Editing commands

  • Insert text [-n] -- Adds the specified text to the start of the line by putting it in the insert buffer. The -n option (in this command and in Append and Change) prevents adding a newline when the line is written out.

  • Append text [-n] -- Adds the specified text to the end of the line by putting it in the append buffer.

  • Change text [-n] -- Changes the line to the specified text by replacing the contents of the edit buffer.

  • Delete -- Clears the edit buffer.

  • Replace [-c count] /pattern/ text -- Replaces the pattern with the specified text. This is the second part of a two-step matching process: first the address matches a line, then Replace searches in the edit buffer and replaces the pattern. The count argument indicates the maximum number of times to perform the replacement in the line. It can be a positive integer or infinity ([[infinity]]). The default count is 1.

Control commands

  • Exit [status] -- Stops StreamEdit with the given error status. The default is 0, which means execution completed with no errors. Any nonzero error status indicates a problem, and unless the built-in MPW variable Exit is set to something other than 0, this will stop execution of the script (if any) from which the StreamEdit command was executed.

  • Next -- Somewhat like the C keyword continue. When a Next command is executed, all pending changes are written out and no more addresses are matched against the current line; that is, StreamEdit immediately goes on to the next line without matching the rest of the rules against the current edit buffer.

  • Set variable text [-i | -a] -- Much like the MPW Shell Set command. The variable is set to the specified text. The -i and -a options allow text to be added to any existing setting of the variable at the start or the end, respectively.

Output commands

  • Print [text] [-appendto | -to file] -- Writes output to a specified file. If text is empty, the current line is printed without modification. The -appendto and -to options write at the end of the file or overwrite the file, respectively. If no file is specified, standard output is used. If the file name is empty, nothing gets printed.

  • Option AutoDelete -- Deletes all input lines, leaving only output from Next and Print commands. You can get the same effect by specifying the -d option on the StreamEdit command line or by including this in the script:
/~/   Delete
The text arguments to these commands are usually literal text, denoted by single or double quotes. There are a few other forms as well:
  • An unquoted variable name can be used, in which case the variable is expanded; no brackets need be (or even may be) supplied.

  • A period means the current input line up to but not including the newline at the end.

  • As discussed in Issue 26, you can use reg. (Option-R) followed by a digit to mean the expression with that number matched in the pattern.

  • You can read text from a file with -from filename, which reads the next line of text from the specified file. The filename is usually literal text, but it could also be a variable, the current input line (denoted by a period), or a reg. expression.

A HYPOTHETICAL EXAMPLE

Let's say you're the director of corporate communications at a major computer maker and, without any warning except for inventory backlogs larger than the gross national products of many developing countries, you experience a sudden transition in chief executive officers, corporate policy, and product line. Your quarterly report (10-Q) is due in the SEC's EDGAR database tomorrow. Fortunately the SEC requires the cutting-edge ASCII format for its filings, and you realize that you can automate 90% of the tedious changes with a single StreamEdit script.
# Change nickname of CEO
/Diesel/
Replace // 'Flyboy'
# Change corporate policy
/1,$/
Replace /capture market share/ 'survive'

# Remove lines referring to obsolete products
/PowerTalk/ || /eWorld/
Delete

# Change developer relations strategy
/third-party developers/
Replace /evangelize/ 'listen to'

# Mark lines referring to old schedules
# with a distinctive string at the start
# of the line for manual editing later
/1996/
Insert 'WHOOPS: '

# Add new final line of report
[[infinity]]
Append 'May God have mercy on our souls.'

CONTROL YOURSELF

StreamEdit is almost too powerful. People have used it for everything, including pretty-printing source code, converting files to HTML, and postprocessing object files for dynamic linking tools. If you use it for finding incriminating passages in coworkers' e-mail, karma may get you, but the limitations of the tool won't. Use your powers for good rather than evil, and a grateful world will thank you.

TIM MARONEY has appeared professionally in newspapers, magazines, compact discs, videotape, and of course, computer software. Tim is a technical lead in human interface software at Apple and is editing a series of books for a horror publisher. His skin burns easily in the sun and tans in the moon. He uses white T-shirts only for house painting and car repair.

Thanks to Arno Gourdol, Alex McKale, and Robert Ulrich for reviewing this column.

 
AAPL
$99.18
Apple Inc.
-1.57
MSFT
$45.90
Microsoft Corpora
-0.46
GOOG
$568.27
Google Inc.
-9.09

MacTech Search:
Community Search:

Software Updates via MacUpdate

Cocktail Family License (5 Macs) 7.6.1 -...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Cocktail 8.0 Beta 2 - General maintenanc...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
QuickBooks 2015 16.0.0.1352 R1 - Financi...
QuickBooks 2015 helps you manage your business easily and efficiently. Organize your finances all in one place, track money going in and out of your business, and spot areas where you can save.... Read more
Mac DVDRipper Pro 5.0.1 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
Apple OS X bash Update 1.0 - Fix for sec...
The OS X bash Update fixes a security flaw in the bash UNIX shell on OS X 10.9.5 (also on OS X 10.8 and 10.7 [see Related Links below]). OS X 10.9.5 or later Downloads for OS X 10.8 and OS X 10.7 in... Read more
SyncTwoFolders 2.0.5 - Syncs two user-sp...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
FinderPop 2.5.7 - Classic Mac utility, n...
FinderPop is a Universal preference pane that extends OS X's contextual menus using a FinderPop Items folder much as the Apple Menu Items folder used to do for the Apple menu. It has other features... Read more
VueScan 9.4.45 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
LibreOffice 4.3.2.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
calibre 2.4 - Complete e-library managem...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more

Latest Forum Discussions

See All

Banner Saga (Games)
Banner Saga 1.0.17 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.17 (iTunes) Description: NOTE: The Banner Saga does NOT run on iPhone 4. iPhone 4S and more modern devices recommended. | Read more »
Beatbuddy HD (Games)
Beatbuddy HD 1.0.2 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.2 (iTunes) Description: **IMPORTANT** Beatbuddy runs only on iPhone 6, 6 Plus, 5, 5c, 5s, iPad 4, iPad Mini Retina and iPad Air. | Read more »
Spirits of Spring (Games)
Spirits of Spring 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: From the creators of the award-winning empathy game, Papo & Yo, comes a tale about finding strength. | Read more »
I am a brave knight (Games)
I am a brave knight 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Do you have ten minutes to live a life? | Read more »
iKeywi - Customizable 5-Row Keyboard (U...
iKeywi - Customizable 5-Row Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $.99, Version: 1.0 (iTunes) Description: Want to add an extra row to your iPhone/iPad? One of the most popular keyboard extension in iOS... | Read more »
Manage Your Cloud – Wunderlist Now Suppo...
Manage Your Cloud – Wunderlist Now Supports Dropbox Posted by Jessica Fisher on October 1st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Nexticy Review
Nexticy Review By Jennifer Allen on October 1st, 2014 Our Rating: :: IDEAL FORM CREATIONiPad Only App - Designed for the iPad Nexticy allows you to make your own forms for research purposes or to organize your business better. It’s... | Read more »
Tiny Troopers: Alliance Marches onto the...
Tiny Troopers: Alliance Marches onto the App Store Tomorrow Posted by Jessica Fisher on October 1st, 2014 [ permalink ] Tiny Troopers: Alliance, by Kukouri, is a | Read more »
HeroCraft Introduces Unlimited Sequel to...
HeroCraft Introduces Unlimited Sequel to WW2: Sandbox. Strategy & Tactics Posted by Jessica Fisher on October 1st, 2014 [ permalink ] | Read more »
RGB Express Review
RGB Express Review By Jennifer Allen on October 1st, 2014 Our Rating: :: DELIGHTFUL PUZZLINGUniversal App - Designed for iPhone and iPad Guide trucks along their delivery routes in RGB Express, a testing but charming puzzle game... | Read more »

Price Scanner via MacPrices.net

ASUS, Lenovo, and Amazon Slug It Out For Tabl...
According to market intelligence firm ABI Research, Apple and Samsung have led the touchscreen tablet market by a substantial margin since Apple energized the category back in 2010. However, ABI says... Read more
Amazon offers 13-inch MacBook Air for $899, $...
Amazon.com has the 13″ 1.4GHz 128GB MacBook Air on sale for $100 off MSRP including free shipping: - 13″ 1.4GHz 128GB MacBook Air: $899.99 Read more
Apple resting On Its iPhone Laurels? – The ‘B...
Apple calls its new iPhone 6 and 6 Plus “The Biggest Advancements in iPhone History,” but does reality live up to the hype? “Seldom have so many waited so breathlessly for so little,” tweeted veteran... Read more
Roundup of Apple Mac and iPad Education disco...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Apple Boycotts German Magazine Computer Bild...
Apple has revoked its PR accreditation of Germany’s Computer Bild, Europe’s best-selling PC magazine, in reaction to Bild’s posting of a “#Bentgate” YouTube video. Axel Telzerow, editor in chief of... Read more
iPhone 6 & iPhone 6 Plus Available in Chi...
Apple has announced that iPhone 6 and iPhone 6 Plus will be available in China beginning Friday, October 17 from the Apple Online Store (http://www.apple.com), Apple’s retail stores, and an expansive... Read more
MacBook Airs on sale for $100 off MSRP, start...
Best Buy has the new 2014 MacBook Airs on sale for $100 off MSRP on their online store. Choose free home shipping or free local store pickup (if available). Prices valid for online orders only, in-... Read more
Apple Releases OS X Mavericks bash Update 1.0...
Apple has released a patch update for OS X Mavericks users to address the recently-detected “Shellshock” security bug in BSD UNIX’s bash shell. Apple says only a few Mac users who had manually... Read more
Pivotal Payments Ready for Apple Pay – FlexPo...
Pivotal Payments, a provider of merchant services and global payment processing solutions, has announced its proprietary FlexPoint platform will support credit and debit transactions through Apple’s... Read more
iStabilizer Announces Tabarm — First Friction...
iStabilizer, a specialist in universal lightweight compact tripods, steady cams, dollies, mounts, and remotes for smartphones, tablets, and cameras, announced today the iStabilizer tabArm, the first... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.