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partial_type_param.go
38 lines (31 loc) · 1.05 KB
/
partial_type_param.go
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package generic
import (
"fmt"
"go/ast"
)
// inferPartialTypeParams infers type parameters for a generic type,
// handling partial specification.
func inferPartialTypeParams(gt *GenericType, indices []ast.Expr, env TypeEnv, ctx *InferenceContext) ([]interface{}, error) {
inferParams := make([]interface{}, len(gt.TypeParams))
for i := range gt.TypeParams {
inferParams[i] = gt.TypeParams[i] // start with the original type parameter
}
for i, index := range indices {
if i >= len(gt.TypeParams) {
return nil, fmt.Errorf("too many type parameters specified for %s", gt.Name)
}
pType, err := InferType(index, env, ctx)
if err != nil {
return nil, err
}
constraint, ok := gt.Constraints[gt.TypeParams[i].(*TypeVariable).Name]
if !ok {
return nil, fmt.Errorf("no constraint for type parameter %s", gt.TypeParams[i].(*TypeVariable).Name)
}
if !checkConstraint(pType, constraint) {
return nil, fmt.Errorf("type argument %v does not satisfy constraint for %v", pType, constraint)
}
inferParams[i] = pType
}
return inferParams, nil
}