go-vise

Constrained Size Output Virtual Machine
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commit 3febf0a6e27578b7449cadff48e505ec49b7acdd
parent 9633672252ead3d4647b1f63863e44a7ffdd3a3d
Author: lash <dev@holbrook.no>
Date:   Sat,  1 Apr 2023 20:39:06 +0100

Add readme section about signals

Diffstat:
MREADME.md | 13+++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md @@ -10,8 +10,8 @@ Original motivation was to create a simple templating renderer for USSD clients, The VM defines the following opcode symbols: * `BACK` - Return to the previous execution frame (will fail if at top frame). It leaves to the state of the execution layer to define what "previous" means. -* `CATCH <symbol> <signal>` - Jump to symbol if signal is set (see `signal` below). -* `CROAK <signal>` - Clear state and restart execution from top if signal is set (see `signal` below). +* `CATCH <symbol> <signal>` - Jump to symbol if signal is set (see `signals` below). +* `CROAK <signal>` - Clear state and restart execution from top if signal is set (see `signals` below). * `LOAD <symbol> <size>` - Execute the code symbol `symbol` and cache the data, constrained to the given `size`. Can be exposed with `MAP` within scope, * `RELOAD <symbol>` - Execute a code symbol already loaded by `LOAD` and cache the data, constrained to the previously given `size` for the same symbol. * `MAP <symbol>` - Expose a code symbol previously loaded by `LOAD` to the rendering client. Roughly corresponds to the `global` directive in Python. @@ -28,6 +28,7 @@ Loaded symbols are not automatically exposed to the rendering client. To expose The associated content of loaded symbols may be refreshed using the `RELOAD` opcode. `RELOAD` only works within the same constraints as `MAP`. However, updated content must be available even if a `MAP` precedes a `RELOAD` within the same frame. + ### External symbol optimizations Only `LOAD` and `RELOAD` should trigger external code side-effects. @@ -40,6 +41,14 @@ In an effort to prevent leaks from unnecessary external code executions, the fol Any code compiler or checked **should** generate an error on any orphaned `LOAD` or `MAP` symbols as described above. +### Signals + +Signal may be set when executing of external code symbols, and may be used as a simple exception mechanism. + +The signal flag arguments should only set a single flag to be tested. If more than one flag is set, the first flag matched will be used as the trigger. + + + ## Rendering The fixed-size output is generated using a templating language, and a combination of one or more _max size_ properties, and an optional _sink_ property that will attempt to consume all remaining capacity of the rendered template.