Task 6 of v0.3 plan (parser + pump class; full --live-values CLI
wiring is Task 7).
parseVarNames(text) extracts variable names from any VAR /
VAR_INPUT / VAR_OUTPUT / VAR_GLOBAL / etc. block. Handles:
- one name per declaration line
- 'AT %QX0.1' location prefix
- := initializer
- inline (* ... *) and // line comments
- multi-line (* ... *) blocks (state threaded across lines)
Doesn't handle the multi-name shorthand 'a, b : INT;' -- vanishingly
rare in practice, cost of getting it wrong is just a missing overlay.
LiveValuesPump owns a setInterval. Each tick:
- reads tui-state.json via the injected readSelection
- reads the POU's .st file from the mirror
- parseVarNames -> per-var read_variable round-trip (errors per-var
are silent, others may succeed)
- writeLiveValues snapshot
Reentrancy guard: if a tick is still in flight when the next
interval fires, skip the new tick rather than queueing. Errors at any
layer are swallowed -- pump must never crash the server.
start()/stop() lifecycle so the server can hand it to the existing
shutdown path.
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