OSTRICH 
An SMT Solver for String Constraints
OSTRICH is an SMT solver for string constraints.
For the POPL 2019 version, please use the popl2019 branch.
Using Ostrich
After installing the Scala Build tool (SBT), you can assemble a JAR file using sbt assembly. To run it, use either the ostrich script in the root folder, or ostrich-client. The latter transparently spins up a server that continuously serves requests from the client script; useful to avoid cold-starting the JVM if you are running many instances.
See ./ostrich -help for more options.
Input Format
OSTRICH accepts constraints written using the SMT-LIB theory of strings. At this point, most of the operators in the theory are supported, but inputs need to be straightline; see this paper for a definition.
In addition to the standardized SMT-LIB operators, OSTRICH can handle a number of further functions.
Additional string functions
| Name | Explanation |
|---|---|
| str.reverse | Reverse a string |
Unary transducers
Finite-state transducers are a general way to introduce further string functions. Examples of functions that can be represented as transducers are encoders, decoders, extraction of sub-strings, removal of white-space characters, etc.
Finite-state transducers can be defined as (mutually) recursive functions, see this file for an example.
Additional regular expression constructors
| Name | Explanation |
|---|---|
| re.from_ecma2020 | Parse a regular expression in textual ECMAScript 2020 format (example) |
| re.case_insensitive | Make any regular expression case insensitive (example) |