hcl/expr_list.go

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package hcl
// ExprList tests if the given expression is a static list construct and,
// if so, extracts the expressions that represent the list elements.
// If the given expression is not a static list, error diagnostics are
// returned.
//
// A particular Expression implementation can support this function by
// offering a method called ExprList that takes no arguments and returns
// []Expression. This method should return nil if a static list cannot
// be extracted. Alternatively, an implementation can support
// UnwrapExpression to delegate handling of this function to a wrapped
// Expression object.
func ExprList(expr Expression) ([]Expression, Diagnostics) {
type exprList interface {
ExprList() []Expression
}
physExpr := UnwrapExpressionUntil(expr, func(expr Expression) bool {
_, supported := expr.(exprList)
return supported
})
if exL, supported := physExpr.(exprList); supported {
if list := exL.ExprList(); list != nil {
return list, nil
}
}
return nil, Diagnostics{
&Diagnostic{
Severity: DiagError,
Summary: "Invalid expression",
Detail: "A static list expression is required.",
Subject: expr.StartRange().Ptr(),
},
}
}