scr2ifm: convert transcripts to IFM map

scr2ifm reads one or more transcripts of an Interactive Fiction game and produces a map of it in IFM format. It works on Infocom-style transcripts—those produced by Inform- and TADS-generated games (and of course Infocom games themselves). The idea is that you play your game in a carefree manner, without worrying about mapping anything, and after the session use scr2ifm to get a map. Well, that’s the theory anyway.

scr2ifm was inspired by Frobot, another transcript-reading mapper. But scr2ifm in combination with IFM does a much better job.

scr2ifm offers two basic ways of mapping: you can create an initial (incomplete) map from your first transcript and then add the rest “by hand”, or you can create a set of transcripts, each exploring different parts of the game, and then merge them all into a final map. Which you choose is up to you.

Options

These are the command-line options for scr2ifm:

-c file

Append the given file of IFM and parameter commands to the end of the map. This allows you to fix various problems in the resulting map.

-o file

Write output to the given file instead of stdout.

-i

Indent the output nicely (according to my definition, anyway). This makes things look better if you’ve added item and task commands. Default is no indentation at all.

-l

Add a comment to each IFM command indicating the file and line number of the transcript command that generated it.

-w

Don’t print warnings.

-h

Print a short usage message and exit.

Operation

scr2ifm works by recognizing several key things in the transcript:

• The commands you type. These are easy to spot, because they are preceded by a prompt (usually >).
• When the current room changes. This is not quite so easy, but still fairly simple. When you enter a new room, a short room title is printed (for example, West of House). The program looks for these short titles in the text that follows a command. First, a line is checked for an invalid format—things that never appear in a title (e.g., ? or !). Then the word count is checked—titles are hardly ever more than 7 or 8 words long. Finally the maximum length of an uncapitalized word is examined—this is almost always 3 or less in titles (the length of “the”).
• When a previously-visited room is visited again. This is the most difficult thing to determine, since anything might have changed in the room since the last visit. If there is a description, an exact description match is tried. If that fails, a substring match is attempted. If that fails, the first few words are examined to see if they match. If there’s no description, an exact room name match is tried. This isn’t as reliable, which is why you should always create a transcript in verbose mode.
• Special IFM commands that are (hopefully) ignored completely by the game.

Some of these checks can be tailored to a particular transcript.

Making transcripts

For best results with scr2ifm, you should follow these guidelines when making a transcript:

• Always use verbose mode. If you don’t, then when you revisit a room you’ve been in before, no description will be printed. In that case, scr2ifm will have to rely on the room name to tell where it is. If there’s more than one room with that name, it’ll get confused (and so will you when you look at the map!).
• After starting the script, look around. Otherwise your starting room may not be included on the map, since the room description may not get printed.
• If there’s a bend in a link (e.g., if you leave a room by going east, and enter the next room from the south) make sure you do the return journey. Otherwise, scr2ifm won’t know about the bend.
• Avoid places where different rooms have the same room description (i.e., mazes). scr2ifm can’t resolve cases like this, and will assume there’s just a single room. Note that this doesn’t exclude all mazes—the “twisty passages, all different” maze from Colossal Cave would still work, since the descriptions are different.
• If you play the game over several sessions, and create several separate transcripts, pay attention to the starting rooms. If a transcript starts in a room already visited in the previous transcript, then its rooms will be added to the same map section. If not, a new map section will be created (and you should use the map command to give it a name).

Some games will be more amenable to scr2ifm than others—in general the ones with reasonable map connections, where each connection makes sense in relation to the others. For these games, the order in which rooms are visited will probably make no difference to the resulting map. But for perverse games (e.g., Colossal Cave, above ground) the order of visiting makes a big difference. In these cases, it’s probably best to avoid trying to get all the connections on the map—you’ll spew forth lots of IFM warnings otherwise, and the map will look awful. Sometimes it’s worth having a second attempt at a transcript, choosing different directions to go in, to see if it improves things.

Another problem with mapping is that some games have these inconvenient things called puzzles, which sometimes block you from exploring everywhere so you can map it properly. Come on, IF authors, let’s get our priorities right!

IFM commands

While you’re making your transcript, you can use a subset of IFM commands to add extra things that scr2ifm will recognize. (Of course, the game almost certainly won’t understand these commands, and will print a suitable indignant reply. But that shouldn’t affect the state of things.) The commands recognized are:

title

Give the map a title. The name must be in double-quotes. This command can appear anywhere, and has the same effect each time.

map

Indicate that the current room starts a new map section with the given name. The name must be in double-quotes. This is useful if it seems like the map divides into different sections (e.g., the floors of a house).

If you use the map command, you’ll end up with two or more map sections. The first map section is the one that contains the very first room, and will have a default name unless you give it one using another map command.

item

Declare an item in the current room. The name must be in double-quotes. If you don’t give it a tag attribute, one is generated automatically by changing all invalid tag characters in the name to underscores.

item [attrs]

Add the given attributes to the last declared item, if any.

item delete

Delete the last declared item, if any.

task

Declare a task in the current room in a similar manner to items. The name must be in double-quotes.

task [attrs]

Add the given attributes to the last declared task, if any.

task delete

Delete the last declared task, if any.

Note that scr2ifm knows almost nothing about IFM command syntax. If there’s a syntax error in a command, you’ll have to manually edit the resulting transcript (or delete the item/task and do it again).

Fixing problems

The map produced by scr2ifm will not be perfect in a lot of cases. When running it through IFM you might get warnings about overlapping rooms, or crossed link lines. These problems are usually fixed by stretching the link lines of some of the rooms. Some overlapping-room problems are caused by the program making a bad choice of direction to put an up/down/in/out connection in. Another problem might be not recognizing when a room is the same as a previously-visited room, because the room description changed too much between visits.

You can fix most of these problems by creating a command file and specifying it with the -c option. There are two types of entry: scr2ifm commands and IFM commands. In a command file, blank lines and comment lines (those starting with a #) are ignored. If a command isn’t recognized as a scr2ifm command, it’s assumed to be an IFM command, and is passed straight into the output verbatim. You can use these to resolve conflicts in the generated map, by stretching certain links or hiding them altogether.

Here’s a list of the commands available:

is_room TEXT

Declare a line of text that is actually the name of a room. Normally room names get recognized properly, but there may be some special cases that aren’t.

not_room TEXT

Declare a line of text that definitely isn’t the name of a room. This is for opposite cases to the above.

use_name TEXT

Use only the room name to decide whether a room has been previously visited. This is for cases where a room description changes too much between visits to be called the same room. Note that this implies that there can only ever be one room with this name.

set_option LETTER

This is a convenience that lets you specify scr2ifm command-line options in the command file instead. E.g., set_option i will indent output nicely.

set_param VAR = VALUE

This evaluates the given Perl expression. You can use this to set various parameters that control how the transcript is parsed (see below). Setting a value of undef will remove that parameter (so that it won’t be used).

Here’s a list of the parameters that control how the transcript is parsed, and their defaults. You can use the scr2ifm set_param command to set them in the command file.

$name_remove

Matched text to remove before seeing if a line of text is a room name. This is for getting rid of stuff like ” (in the dodgem car)”. Default: \s+\(.+\)

$name_maxwords

Maximum no. of words in a room name. Default: 8

$name_maxuncap

Maximum length of an uncapitalized word in a room name. Default: 3

$name_invalid

Regexp which, if matched, signals an invalid room name. Default: [.!?"]

$desc_minwords

Minimum no. of matching words required to match a room description. Default: 20

$cmd_prompt

Regexp matching a command prompt. Default: ^>\s*

$cmd_look

Regexp matching a ‘look’ command (case-insensitive). Default: ^l(ook)?$

$cmd_undo

Regexp matching an UNDO command (case-insensitive). It’s assumed that only a single level of UNDO is available. Default: ^undo$

$cmd_teleport

Regexp matching commands that are known to cause a teleport to an arbitrary room (case-insensitive). Default: ^(restart|restore)$

Writing the map

Output from scr2ifm is as follows. First, if the title of the map was specified with the title command, it is printed. Then, if there’s more than one map section, a list of map section titles is printed.

Next, there’s a list of IFM commands derived from the transcript. Each time a new room is seen, a room command is output for it. Each room is given a tag name formed by the initials of each capitalized word in its name. To make tags unique, the second and subsequent occurrences of a tag name have that number appended. For example, room “West of House” would get tag WH.

If a movement command was up, down, in or out, then a compass direction is chosen for it that doesn’t clash with other rooms (if possible) and the go attribute is used to mark its real direction. If a movement command isn’t recognized, the same is done except this time the cmd attribute is used to record the command instead.

If movement is seen between two already-visited rooms, a link command is output (or a join, if the rooms appear to be on different map sections). Link tags are built by concatenating the room tags of the linked rooms with an underscore in between. Link movement is dealt with in the same manner as for rooms.

If the special item or task commands are seen, then an item or task command is output following the room that it appears in. If an item or task hasn’t been given a tag, it is assigned one. The tag is made by translating all invalid tag characters in the name to underscores, capitalizing (to avoid clashes with IFM commands) and, if the tag clashes with a previously-defined tag, adding a numerical suffix to make it unique. For example, “black rod” might get a tag Black_rod_2.

Finally, the IFM commands from the file indicated by the -c option are echoed (if any).

Example session

Here’s a simple example of scr2ifm in action on Colossal Cave. First, the transcript in file advent.scr (with annotation):

Start of a transcript of
ADVENTURE
The Interactive Original
By Willie Crowther and Don Woods (1977)
David M. Baggett's 1993 reconstruction, ported by Graham Nelson
Release 3 / Serial number 951220 / Inform v1502 Library 5/12
Interpreter 1 Version B / Library serial number 951024

>verbose
ADVENTURE is now in its "verbose" mode, which always gives
long descriptions of locations (even if you've been there
before).

>l

At End Of Road
You are standing at the end of a road before a small brick
building. Around you is a forest. A small stream flows out
of the building and down a gully.

The previous two commands are recommended after starting the transcript.

>e

Inside Building
You are inside a building, a well house for a large spring.

There are some keys on the ground here.

There is tasty food here.

There is a shiny brass lamp nearby.

There is an empty bottle here.

>item "keys"
That's not a verb I recognise.

>item "food"
That's not a verb I recognise.

>item "lamp"
That's not a verb I recognise.

>item "bottle"
That's not a verb I recognise.

The previous four commands declare the given items to the program. You don’t have to bother with this if you don’t want item locations on your map.

>get all
stream: You have nothing in which to carry the water.
well house: That's hardly portable.
spring: That's hardly portable.
pair of 1 foot diameter sewer pipes: That's hardly portable.
set of keys: Taken.
tasty food: Taken.
brass lantern: Taken.
small bottle: Taken.

>w

At End Of Road
You are standing at the end of a road before a small brick
building. Around you is a forest. A small stream flows out
of the building and down a gully.

>s

In A Valley
You are in a valley in the forest beside a stream tumbling
along a rocky bed.

>s

At Slit In Streambed
At your feet all the water of the stream splashes into a
2-inch slit in the rock. Downstream the streambed is bare
rock.

>s

Outside Grate
You are in a 20-foot depression floored with bare dirt. Set
into the dirt is a strong steel grate mounted in concrete. A
dry streambed leads into the depression.

Note that in this game we don’t go in all possible directions—there’s no logic to the connections, and it’d just make a complete mess on the map.

>unlock grate
What do you want to unlock the steel grate with?

>keys
You unlock the steel grate.

>task "Unlock grate" need Keys
That's not a verb I recognise.

That last command declared a task—again, you don’t have to bother with this if you don’t want to.

>open grate
You open the steel grate.

>task "Open grate" after last
That's not a verb I recognise.

>d

Below the Grate
You are in a small chamber beneath a 3x3 steel grate to the
surface. A low crawl over cobbles leads inward to the west.

The grate stands open.

>w

In Cobble Crawl
You are crawling over cobbles in a low passage. There is a
dim light at the east end of the passage.

There is a small wicker cage discarded nearby.

>item "cage"
That's not a verb I recognise.

>get cage
Taken.

>w

Darkness
It is pitch dark, and you can't see a thing.

>undo
In Cobble Crawl
[Previous turn undone.]

Oops! Stumbled into the dark by mistake. Without the UNDO, that would have meant Darkness appeared on the map as a room.

>turn lamp on
You switch the brass lantern on.

>w
In Debris Room
You are in a debris room filled with stuff washed in from
the surface. A low wide passage with cobbles becomes plugged
with mud and debris here, but an awkward canyon leads upward
and west.

A note on the wall says, "Magic word XYZZY."

A three foot black rod with a rusty star on one end lies
nearby.

>item "black rod" tag Rod
That's not a verb I recognise.

>xyzzy

Inside Building
You are inside a building, a well house for a large spring.

Goodness me! That was unexpected—we’ve been teleported. The link almost certainly won’t look good on the map. We have the option of UNDOing, right now, or fixing the map later. Let’s do the latter.

>xyzzy

In Debris Room
You are in a debris room filled with stuff washed in from
the surface. A low wide passage with cobbles becomes plugged
with mud and debris here, but an awkward canyon leads upward
and west.

A note on the wall says, "Magic word XYZZY."

A three foot black rod with a rusty star on one end lies
nearby.

>get rod
Taken.

>w

Sloping E/W Canyon
You are in an awkward sloping east/west canyon.

>w

Orange River Chamber
You are in a splendid chamber thirty feet high. The walls
are frozen rivers of orange stone. An awkward canyon and a
good passage exit from east and west sides of the chamber.

A cheerful little bird is sitting here singing.

>item "bird"
That's not a verb I recognise.

>unscript

End of transcript.

Ok, now to create a map. To do that, use this command:

scr2ifm -o advent.ifm advent.scr

To check for problems, just type:

ifm advent.ifm

On the first run through, there are complaints about an overlapping room, due to a bad choice of direction for the “down” link from Outside Grate, and the expected problems with the link between the Debris Room and the Building. A command file, advent.cmd, will fix these problems:

# Fix bad choice of direction.
link BG dir s;

# Hide "xyzzy" link.
link IDR_IB hidden;

# Replace it with join.
join IDR to IB cmd "xyzzy";

Now, if we invoke:

scr2ifm -o advent.ifm -i -c advent.cmd advent.scr

we get the following map:

## IFM map created by scr2ifm.pl

## Commands generated by transcript.
room "At End Of Road" tag AEOR;

room "Inside Building" dir e from AEOR tag IB;
  item "keys" tag Keys;
  item "food" tag Food;
  item "lamp" tag Lamp;
  item "bottle" tag Bottle;

room "In A Valley" dir s from AEOR tag IAV;

room "At Slit In Streambed" dir s from IAV tag ASIS;

room "Outside Grate" dir s from ASIS tag OG;
  task "Unlock grate" need Keys tag Unlock_grate;
  task "Open grate" after last tag Open_grate;

room "Below the Grate" dir n from OG go down tag BG;

room "In Cobble Crawl" dir w from BG tag ICC;
  item "cage" tag Cage;

room "In Debris Room" dir w from ICC tag IDR;
  item "black rod" tag Rod;

link IDR to IB dir n s cmd "xyzzy" tag IDR_IB;

room "Sloping E/W Canyon" dir w from IDR tag SEC;

room "Orange River Chamber" dir w from SEC tag ORC;
  item "bird" tag Bird;

## Customization commands.
link BG dir s;
link IDR_IB hidden;
join IDR to IB cmd "xyzzy";

Printed, it looks like this:

Limitations

Here’s a list of things that scr2ifm doesn’t currently deal with:

• Mazes. Different maze rooms that look identical (i.e., have identical names and descriptions) will simply appear as a single room.
• One-way links. These aren’t detected, so you’ll have to add the appropriate IFM attribute yourself (in a command file, or by fixing the map directly).