Chapter 8 Runtime Library

8.1 Predefined mappings

8.1.1 Builtin sorts

The system comes with several predefined signature-mappings for C, Java and Caml. Among them, let us mention:

boolean.tom (true or false)
char.tom (written 'a', 'b', etc.)
double.tom (using Java grammar for double)
float.tom (using Java grammar for float)
int.tom (written 1, 2, 3, etc.)
long.tom (written 1l or 1L, etc.)
string.tom (written "a", "ab", etc.)

These mappings define, for each builtin sort of the host language, an algebraic sort that can be used in a %match or a signature definition construct. Thus, builtin values, such as f(5), g('a') or h("foo"), can be used in patterns.

The string.tom mapping is interesting because it provides an associative operator (concString) which allows the programmer to consider a string as a list of characters. Thus, the string "foo" can be seen as the algebraic object concString('f','o','o'). By using this mapping, it becomes possible to perform pattern matching against the content of a string. The pattern concString('f',X*) will match any string which begins with the character 'f'. By using the unnamed-symbol capability, this pattern can be written: ('f',X*) instead of concString('f',X*).

To match any string which begins with the substring "fo", the corresponding pattern should be ('f','o',X*). To simplify the definitions of such patterns, Tom supports an exception which allows the programmer to write ('fo',X*) instead. Internally, the ill-formed character 'fo' is expanded into the list ('f','o'). Thus, the annotated notation y@'fo' is expanded into (y@'f',y@'o'), and thus may be dangerous to use in this case.

In addition to these mappings, several other predefined mappings come with the system:

aterm.tom and atermlist.tom provide a mapping to the C and Java version of the ATerm Library
caml/list.tom provides a mapping to the builtin notion of List in Caml
java/dom.tom provides a mapping to the Java version of the DOM Library

8.1.2 Java

To help manipulating Java data-structures, Tom provides several mappings for the Java Runtime Library. The naming convention follows Java's one:

  java
  o--- Character.tom
  +--- util
       o--- ArrayList.tom
       o--- HashMap.tom
       o--- HashSet.tom
       o--- LinkedList.tom
       o--- MapEntry.tom
       o--- TreeMap.tom
       o--- TreeSet.tom
       +--- types
            o--- AbsractCollection.tom
            o--- AbsractList.tom
            o--- AbsractSequentialList.tom
            o--- AbsractSet.tom
            o--- ArrayList.tom
            o--- Collection.tom
            o--- HashMap.tom
            o--- HashSet.tom
            o--- LinkedHashSet.tom
            o--- Map.tom
            o--- Object.tom
            o--- Stack.tom
            o--- TreeMap.tom
            o--- TreeSet.tom
            o--- Vector.tom
            o--- WeakHashMap.tom

The directory types contains only %typeterm declarations.

8.1.3 Strategies

To support strategies, Tom provides a predefined mapping to allow the description of strategies.

mustrategy.tom: maps the basic strategies classes, and provides a mu operator to express the recursion as well a MuVar(v:String) operator to allow the definition of complex strategies as described in Section 7.3.

8.1.4 Bytecode

To support the analysis and transformation of Java bytecode programs, Tom provides several mappings and libraries:

adt/bytecode/Bytecode.tom provides an abstract syntax tree implementation to represent any Java bytecode program. In addition, a Gom library is also provided
adt/bytecode/_Bytecode.tom contains the congruence strategies associated to the AST
java/bytecode/cfg.tom defines new strategies that allows to explore the control flow graph.

8.2 XML

To support the transformation of Xml documents, Tom provides a specific syntax for defining patterns, as well as several predefined mappings:

dom.tom: maps Xml notation to a Java implementation of the DOM library
dom_1.5.tom: maps Xml notation to a Java (version 1.5) implementation of the DOM library
TNode.tom: maps Xml notation to an ATerm based representation, generated by Gom

See Section 5.4 for a detailed description of the Xml facilities offered by Tom.