expression.automaton(algo="auto")

Generate an automaton from an expression.

The algo can be:

• "auto": currently equivalent to "expansion", eventually should mix "standard" for basic expressions (faster) and "expansion" otherwise (more general).
• "derivation": use derivation-based expression.derived_term, trim and stripped.
• "derived_term": same as "expansion"
• "expansion": use expansion-based expression.derived_term, trim and stripped.
• "standard": use expression.standard.
• "thompson": use expression.thompson.
• "zpc": use expression.zpc, trim.
• "zpc_compact": use expression.zpc, "compact" version, trim.

See also:

• expression.derived_term
• expression.standard
• expression.thompson
• expression.zpc

Examples

import vcsn
e = vcsn.Q.expression('\e+<2>a+<3>b')
e

$\varepsilon + \left\langle 2 \right\rangle \,a + \left\langle 3 \right\rangle \,b$

e.automaton('derived_term')

e.automaton('standard')

e.automaton('thompson')

e.automaton('zpc')

e.automaton('zpc_compact')

Trimming

The automata are guaranteed to be trim, even if the algorithm used by automaton generated useless states.

e = vcsn.Q.expression('abc&abd')
e.derived_term()

e.automaton('derived_term')

e = vcsn.Q.expression('a?')
e.zpc()

e.automaton('zpc')