util

package
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Published: Aug 14, 2019 License: BSD-3-Clause Imports: 15 Imported by: 0

Documentation

Overview

Package util contains utility functions.

Index

Constants

View Source
const (
	MaxUint = ^uint(0)
	MinUint = 0
	MaxInt  = int(MaxUint >> 1)
	MinInt  = -MaxInt - 1
)

Limit values for uint and int.

NOTE: The math package contains similar constants for explicitly sized integer types, but lack those for uint and int.

Variables

View Source
var (
	CulpritLineBegin   = "\033[1;4m"
	CulpritLineEnd     = "\033[m"
	CulpritPlaceHolder = "^"
)

Variables controlling the style of the culprit.

View Source
var ErrClaimFileBadPattern = errors.New("ClaimFile: pattern must contain exactly one asterisk")

ErrClaimFileBadPattern is thrown when the pattern argument passed to ClaimFile does not contain exactly one asterisk.

View Source
var ErrIndexOutOfRange = errors.New("substring out of range")

ErrIndexOutOfRange is returned when out-of-range errors occur.

Functions

func CamelToDashed

func CamelToDashed(camel string) string

CamelToDashed converts a CamelCaseIdentifier to a dash-separated-identifier, or a camelCaseIdentifier to a -dash-separated-identifier.

func Catch

func Catch(perr *error)

Catch tries to catch an error thrown by Throw and stop the panic. If the panic is not caused by Throw, the panic is not stopped. It should be called directly from defer.

func CeilDiv

func CeilDiv(a, b int) int

CeilDiv computes ceil(float(a)/b) without using float arithmetics.

func ClaimFile

func ClaimFile(dir, pattern string) (*os.File, error)

ClaimFile takes a directory and a pattern string containing exactly one asterisk (e.g. "a*.log"). It opens a file in that directory, with a filename matching the template, with "*" replaced by a number. That number is one plus the largest of all existing files matching the template. If no such file exists, "*" is replaced by 1. The file is opened for read and write, with permission 0666 (before umask).

For example, if the directory /tmp/elvish contains a1.log, a2.log and a9.log, calling ClaimFile("/tmp/elvish", "a*.log") will open a10.log. If the directory has no files matching the pattern, this same call will open a1.log.

This function is useful for automatically determining unique names for log files. Unique filenames can also be derived by embedding the PID, but using this function preserves the chronical order of the files.

This function is concurrency-safe: it always opens a new, unclaimed file and is not subject to race condition.

func DeepPrint

func DeepPrint(x interface{}) string

DeepPrint is like printing with the %#v formatter of fmt, but it prints pointer fields recursively.

func DoesntThrow

func DoesntThrow(f func()) bool

DoesntThrow returns whether calling f does not throw anything. It is useful for testing.

func DontSearch

func DontSearch(exe string) bool

DontSearch determines whether the path to an external command should be taken literally and not searched.

func Errors

func Errors(errs ...error) error

Errors concatenate multiple errors into one. If all errors are nil, it returns nil. If there is one non-nil error, it is returned. Otherwise the return value is a MultiError containing all the non-nil arguments. Arguments of the type MultiError are flattened.

func FindContext

func FindContext(text string, pos int) (lineno, colno int, line string)

FindContext takes a position in a text and finds its line number, corresponding line and column numbers. Line and column numbers are counted from 0. Used in diagnostic messages.

func FindFirstEOL

func FindFirstEOL(s string) int

FindFirstEOL returns the index of the first '\n'. When there is no '\n', the length of s is returned.

func FindLastSOL

func FindLastSOL(s string) int

FindLastSOL returns an index just after the last '\n'.

func ForceWcwidth

func ForceWcwidth(s string, width int) string

ForceWcwidth forces the string s to the given display width by trimming and padding.

func FullNames

func FullNames(dir string) []string

FullNames returns the full names of non-hidden files under a directory. The directory name should end in a slash. If the directory cannot be listed, it returns nil.

The output should be the same as globbing dir + "*". It is used for testing globbing.

func GetHome

func GetHome(uname string) (string, error)

GetHome finds the home directory of a specified user. When given an empty string, it finds the home directory of the current user.

func GetLogger

func GetLogger(prefix string) *log.Logger

GetLogger gets a logger with a prefix.

func Getwd

func Getwd() string

Getwd returns path of the working directory in a format suitable as the prompt.

func HasSubseq

func HasSubseq(s, t string) bool

HasSubseq determines whether s has t as its subsequence. A string t is a subsequence of a string s if and only if there is a possible sequence of steps of deleting characters from s that result in t.

func InTempDir

func InTempDir(f func(string))

InTempDir is like WithTempDir, but also cd into the directory before running the function, and cd backs after running the function if possible.

It panics if it could not get the working directory or change directory.

It is useful in tests.

func IsExecutable

func IsExecutable(path string) bool

IsExecutable determines whether path refers to an executable file.

func MatchSubseq

func MatchSubseq(s, pattern string) bool

MatchSubseq returns whether pattern is a subsequence of s.

func NthRune

func NthRune(s string, n int) (rune, error)

NthRune returns the n-th rune of s.

func OverrideWcwidth

func OverrideWcwidth(r rune, w int)

OverrideWcwidth overrides the wcwidth of a rune to be a specific non-negative value. OverrideWcwidth panics if w < 0.

func PCall

func PCall(f func()) (e error)

PCall calls a function and catches anything Thrown'n and returns it. It does not protect against panics not using Throw, nor can it distinguish between nothing thrown and Throw(nil).

func PprintError

func PprintError(err error)

PprintError pretty-prints an error if it implements Pprinter, and prints it in bold and red otherwise.

func SetOutput

func SetOutput(newout io.Writer)

SetOutput redirects the output of all loggers obtained with GetLogger to the new io.Writer. If the old output was a file opened by SetOutputFile, it is closed.

func SetOutputFile

func SetOutputFile(fname string) error

SetOutputFile redirects the output of all loggers obtained with GetLogger to the named file. If the old output was a file opened by SetOutputFile, it is closed. The new file is truncated. SetOutFile("") is equivalent to SetOutput(ioutil.Discard).

func SubstringByRune

func SubstringByRune(s string, low, high int) (string, error)

SubstringByRune returns the range of the i-th rune (inclusive) through the j-th rune (exclusive) in s.

func Throw

func Throw(err error)

Throw panics with err wrapped properly so that it can be catched by Catch.

func Throws

func Throws(f func(), e error) bool

Throws returns whether calling f throws out a certain error (using Throw). It is useful for testing.

func ThrowsAny

func ThrowsAny(f func()) bool

ThrowsAny returns whether calling f throws out anything that is not nil. It is useful for testing.

func TildeAbbr

func TildeAbbr(path string) string

TildeAbbr abbreviates the user's home directory to ~.

func TrimEachLineWcwidth

func TrimEachLineWcwidth(s string, width int) string

TrimEachLineWcwidth trims each line of s so that it is no wider than the specified width.

func TrimWcwidth

func TrimWcwidth(s string, wmax int) string

TrimWcwidth trims the string s so that it has a width of at most wmax.

func UnoverrideWcwidth

func UnoverrideWcwidth(r rune)

UnoverrideWcwidth removes the override of a rune.

func Wcswidth

func Wcswidth(s string) (w int)

Wcswidth returns the width of a string when displayed on the terminal, assuming no soft line breaks.

func Wcwidth

func Wcwidth(r rune) int

Wcwidth returns the width of a rune when displayed on the terminal.

func WithTempDir

func WithTempDir(f func(string))

WithTempDir is like with WithTempDirs, except that it always creates one temporary directory and pass the function a string instead of []string.

func WithTempDirs

func WithTempDirs(n int, f func([]string))

WithTempDirs creates a requested number of temporary directories and runs a function, passing the paths of the temporary directories; the passed paths all have their symlinks resolved using filepath.EvalSymlinks. After the function returns, it removes the temporary directories. It panics if it cannot make a temporary directory, and prints an error message to stderr if it cannot remove the temporary directories.

It is useful in tests.

Types

type MultiError

type MultiError struct {
	Errors []error
}

MultiError pack multiple errors into one error.

func (MultiError) Error

func (es MultiError) Error() string

type Pprinter

type Pprinter interface {
	// Pprint takes an indentation string and pretty-prints.
	Pprint(indent string) string
}

Pprinter wraps the Pprint function.

type SourceRange

type SourceRange struct {
	Name   string
	Source string
	Begin  int
	End    int
	// contains filtered or unexported fields
}

SourceRange is a range of text in a source code. It can point to another SourceRange, thus forming a linked list. It is used for tracebacks.

func NewSourceRange

func NewSourceRange(name, source string, begin, end int) *SourceRange

NewSourceRange creates a new SourceRange.

func (*SourceRange) Pprint

func (sr *SourceRange) Pprint(sourceIndent string) string

Pprint pretty-prints a SourceContext.

func (*SourceRange) PprintCompact

func (sr *SourceRange) PprintCompact(sourceIndent string) string

PprintCompact pretty-prints a SourceContext, with no line break between the source position range description and relevant source excerpt.

type Thrown

type Thrown struct {
	Wrapped error
}

Thrown wraps an error that was raised by Throw, so that it can be recognized by Catch.

func (Thrown) Error

func (t Thrown) Error() string

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