Design a small API that stores a string and answers simple queries about it.
Problem
Implement a tiny text utility that supports a few operations over an internal string value.
You will define a class-like object with methods that let a caller:
- create the object with an initial string,
- update the stored string,
- compare the stored string against another string,
- and check whether the stored string contains a given substring.
The goal is to keep the interface simple and make each operation return a boolean result when appropriate.
Notes
- Comparison should be exact and case-sensitive.
- Substring checks should also be exact and case-sensitive.
- If the stored string is changed, later queries should use the updated value.
Input Format
The input is represented by method calls on a text utility object:
- initialize with one string,
- update the stored string with another string,
- query equality against a provided string,
- query whether a provided substring exists inside the stored string.
Because this is a design-style problem, there is no single standalone input format.
Output Format
For query methods, return a boolean indicating whether the condition is satisfied.
- Equality query:
trueif the stored string exactly matches the provided string. - Substring query:
trueif the provided substring appears anywhere in the stored string.
Update methods do not return a value.
Constraints
- Strings may be empty.
- All comparisons are case-sensitive.
- Use straightforward string operations; no special normalization is required.
- Exact limits are not specified in the source context.
Example 1
Input
Initialize with `"hello"`. Query equality with `"hello"`. Query substring with `"ell"`. Update the stored string to `"world"`. Query equality with `"hello"`. Query substring with `"or"`.
Output
true true false true
Explanation
The first string matches exactly, and it contains "ell". After updating to "world", equality with "hello" becomes false, but "or" is still present.
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