The PMAP System

Stop Tokens

How Pseudo knows where an expression ends and the next keyword begins.

The Problem

In a pattern like:

text

for {var:name} from {start:expr} to {end:expr}

How does the matcher know where {start:expr} ends and to begins?

Answer: stop tokens. The matcher collects expression tokens until it sees a token that is a known keyword (a stop token).

How Stop Tokens Are Built

Pseudo extracts all literal words from all patterns in the loaded .pmap
Builds a global stop-token set from those words
When matching :expr, tokens are collected until a stop-token is seen, the line ends, or brackets close

Default Stop Tokens

These come from the literal tokens in default.pmap:

for, from, to, step, in, each, every, while, until, if, when,
check, given, else, otherwise, return, give, back, and, or, not,
as, is, then, loop, repeat, function, func, define, def, procedure

An Expression Stops When

A stop-token is found (keyword boundary)
End of line
A colon (block opener)
A matching closing bracket ) ] }

Examples

Stop at keyword

pseudo

for i from 0 to n step 2
#         ↑──────↑ start:expr = "0" - stops at "to"
#                    ↑ end:expr = "n" - stops at "step"
#                           ↑ step:expr = "2"

Stop at end of line

pseudo

print arr[i] + arr[j] * 2
#     ↑────────────────────↑ value:expr = "arr[i] + arr[j] * 2"
#     no stop-token → collects to end of line

Stop at bracket close

pseudo

$input("Enter name:") as string
#             ↑─────↑ prompt:any = "Enter name:" - stops at )
#                        ↑ type:word = "string"

Custom PMAP Expands Stop Tokens

When you add new patterns to a custom .pmap, any new literal words you introduce automatically become stop tokens:

custom.pmap

[FOR_LOOP]
count {var:name} from {start:expr} until {end:expr}
# "count" and "until" are now stop tokens

⚠

Be careful with common wordsIf you add a common word like the or of as a literal token in a pattern, it becomes a stop token and will terminate expressions that contain those words.