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43 lines
1.3 KiB
Go
43 lines
1.3 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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//go:build go1.18
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// +build go1.18
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package hcl
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// This file contains additional diagnostics-related symbols that use the
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// Go 1.18 type parameters syntax and would therefore be incompatible with
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// Go 1.17 and earlier.
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// DiagnosticExtra attempts to retrieve an "extra value" of type T from the
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// given diagnostic, if either the diag.Extra field directly contains a value
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// of that type or the value implements DiagnosticExtraUnwrapper and directly
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// or indirectly returns a value of that type.
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//
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// Type T should typically be an interface type, so that code which generates
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// diagnostics can potentially return different implementations of the same
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// interface dynamically as needed.
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//
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// If a value of type T is found, returns that value and true to indicate
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// success. Otherwise, returns the zero value of T and false to indicate
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// failure.
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func DiagnosticExtra[T any](diag *Diagnostic) (T, bool) {
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extra := diag.Extra
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var zero T
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for {
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if ret, ok := extra.(T); ok {
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return ret, true
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}
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if unwrap, ok := extra.(DiagnosticExtraUnwrapper); ok {
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// If our "extra" implements DiagnosticExtraUnwrapper then we'll
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// unwrap one level and try this again.
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extra = unwrap.UnwrapDiagnosticExtra()
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} else {
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return zero, false
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}
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}
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}
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