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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package common
import (
"fmt"
"strings"
"unicode/utf8"
"golang.org/x/text/width"
)
// NewError creates an error associated with an expression id with the given message at the given location.
func NewError(id int64, message string, location Location) *Error {
return &Error{Message: message, Location: location, ExprID: id}
}
// Error type which references an expression id, a location within source, and a message.
type Error struct {
Location Location
Message string
ExprID int64
}
const (
dot = "."
ind = "^"
// maxSnippetLength is the largest number of characters which can be rendered in an error message snippet.
maxSnippetLength = 16384
)
var (
wideDot = width.Widen.String(dot)
wideInd = width.Widen.String(ind)
)
// ToDisplayString decorates the error message with the source location.
func (e *Error) ToDisplayString(source Source) string {
var result = fmt.Sprintf("ERROR: %s:%d:%d: %s",
source.Description(),
e.Location.Line(),
e.Location.Column()+1, // add one to the 0-based column for display
e.Message)
if snippet, found := source.Snippet(e.Location.Line()); found && len(snippet) <= maxSnippetLength {
snippet := strings.Replace(snippet, "\t", " ", -1)
srcLine := "\n | " + snippet
var bytes = []byte(snippet)
var indLine = "\n | "
for i := 0; i < e.Location.Column() && len(bytes) > 0; i++ {
_, sz := utf8.DecodeRune(bytes)
bytes = bytes[sz:]
if sz > 1 {
indLine += wideDot
} else {
indLine += dot
}
}
if _, sz := utf8.DecodeRune(bytes); sz > 1 {
indLine += wideInd
} else {
indLine += ind
}
result += srcLine + indLine
}
return result
}
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