containsconst

Containsconst is a generic predicate or utility used in programming languages and data-analysis tools to determine whether a given expression, data structure, or program fragment contains at least one constant value. In this context, a constant refers to a literal or fixed value such as a number, string, boolean, or null that does not depend on runtime input.

In practice, containsconst returns true if any leaf element of the structure is a constant. For example, an arithmetic expression like 3 + x contains constants (the literal 3), while an expression like x + y contains no constants if both x and y are variables. The exact definition of what counts as a constant can vary by language or analysis framework, but typically literals and fixed identifiers are included.

Applications and uses include compiler optimizations, static analysis, and query processing. Compilers may use containsconst to identify subexpressions suitable for constant folding, where a constant subexpression is evaluated at compile time. Static analysis tools may rely on containsconst to determine whether a computation depends on input, which can influence security checks or optimization decisions. In query engines, a similar check helps push constant expressions into earlier stages of evaluation, reducing runtime work.

Algorithmically, containsconst is usually implemented as a recursive traversal of the expression or data structure, using a visitor pattern or tree walk. A simple version is: if the current node is a constant, return true; otherwise, recursively check each child, returning true if any child contains a constant; if no constants are found, return false. The typical time complexity is linear in the size of the structure, and care is needed to handle cycles or shared nodes.

Related concepts include isConstant, containsConstantExpression, and constant folding.