We introduce the novel Nearest Pattern Constrained String (NPCS) problem of finding a minimum set Q of character mutation, insertion, and deletion edit operations sufficient to modify a string x to contain all contiguous substrings in a pattern set P and no contiguous substrings in a forbidden pattern set F . Letting Σ be the alphabet of allowed characters, and letting η and ϒ be the longest string length and sum of all string lengths in P ∪ F , respectively, we show that NPCS is fixed-parameter tractable in | P | with time complexity O ( 2 | P | ⋅ ϒ ⋅ | Σ | ⋅ ( | P | + η ) ( | x | + 1 ) ) . Additionally, we consider a generalization of the NPCS problem in which we allow for constraints based on the membership of substrings in regular languages. In particular, we introduce a problem we denote String Editing under Substring in Language Constraints (StrEdit-SILC), where provided a wildcard-free string x ∈ Σ ⁎ , a finite set of regular languages R = { L 1 , L 2 , … } , and a regular language L F , the objective is to find a minimum cost set of mutation, insertion, and deletion edit operations Q that suffice to convert the input string x into a string x ′ ∈ Σ ⁎ , where no substring has membership in L F , and ∀ L i ∈ R , there exists a substring in L i . Here, letting Ψ and ϖ be the sum of all regular expression lengths and longest regular expression length for languages in R ∪ { L F } , respectively, and letting C m i d ∈ N be the maximum cost of an edit operation, we show that StrEdit-SILC is fixed-parameter tractable with respect to Ψ, having time complexity O ( 2 Ψ ⋅ | x | ⋅ ( ϖ ⋅ | Σ | + C m i d ) ) . However, we also show that StrEdit-SILC is MAX-SNP-hard and otherwise difficult to approximate under stringent constraints.