- previously simply reused the scan token, which works fine for
non-nested tokenizations but becomes too fragile with nesting.
Now changed to use tagged unions that can be copied about
and still retain some rudimentary knowledge of their types,
which can be manually triggered with a destroy() call.
- provide an 'identifier' non-terminal as an additional catch
to avoid potential leakage on parsing failure.
- adjust lemon rules and infrastructure:
- use %token to predefine standard tokens.
Will reduce some noise on the generated headers by retaining the
order on the initial token names.
- Define BIT_NOT, internal token rename NOT -> LNOT
- handle non-terminal vector values.
Support vector::x, vector::y and vector::z constants
- permit fieldExpr access to time().
Probably not usable or useful for an '#eval' expression,
but useful for a Function1.
- provisioning for hooks into function calls. Establishes token
names for next commit(s).
- snGrad, internalField, neighbourField.
Functional use as per swak: "... + internalField(T) ..."
ENH: additional volume/patch expressions
- deltaT()
STYLE: rename exprDriverWriter -> fvExprDriverWriter
- the original class name was a misnomer since it holds a reference
to fvExprDriver
BUG: expression faceToPoint/pointToFace definitions were flipped
ENH: refactor expression hierarchy and code style
- handle TimeState reference at the top-level for simpler derivations
- unified internal search parameters (cruft)
For example,
```
entry #eval 10 { vector(rand(), 0, 0) };
```
ENH: be more generous and ignore trailing ';' in expressions
STYLE: adjust parse token name for tensor::I
