funcGoVersion¶added ingo1.21.0

func GoVersion(xExpr)string

GoVersion returns the minimum Go version implied by a given build expression.If the expression can be satisfied without any Go version tags, GoVersion returns an empty string.

For example:

GoVersion(linux && go1.22) = "go1.22"GoVersion((linux && go1.22) || (windows && go1.20)) = "go1.20" => go1.20GoVersion(linux) = ""GoVersion(linux || (windows && go1.22)) = ""GoVersion(!go1.22) = ""

GoVersion assumes that any tag or negated tag may independently be true,so that its analysis can be purely structural, without SAT solving.“Impossible” subexpressions may therefore affect the result.

For example:

GoVersion((linux && !linux && go1.20) || go1.21) = "go1.20"

funcIsGoBuild¶

func IsGoBuild(linestring)bool

IsGoBuild reports whether the line of text is a “//go:build” constraint.It only checks the prefix of the text, not that the expression itself parses.

funcIsPlusBuild¶

func IsPlusBuild(linestring)bool

IsPlusBuild reports whether the line of text is a “// +build” constraint.It only checks the prefix of the text, not that the expression itself parses.

funcPlusBuildLines¶

func PlusBuildLines(xExpr) ([]string,error)

PlusBuildLines returns a sequence of “// +build” lines that evaluate to the build expression x.If the expression is too complex to convert directly to “// +build” lines, PlusBuildLines returns an error.

typeAndExpr¶

type AndExpr struct {X, YExpr}

An AndExpr represents the expression X && Y.

func (x *AndExpr) Eval(ok func(tagstring)bool)bool

func (x *AndExpr) String()string

typeExpr¶

type Expr interface {// String returns the string form of the expression,// using the boolean syntax used in //go:build lines.String()string// Eval reports whether the expression evaluates to true.// It calls ok(tag) as needed to find out whether a given build tag// is satisfied by the current build configuration.Eval(ok func(tagstring)bool)bool// contains filtered or unexported methods}

An Expr is a build tag constraint expression.The underlying concrete type is *AndExpr, *OrExpr, *NotExpr, or *TagExpr.

func Parse(linestring) (Expr,error)

typeNotExpr¶

type NotExpr struct {XExpr}

A NotExpr represents the expression !X (the negation of X).

func (x *NotExpr) Eval(ok func(tagstring)bool)bool

func (x *NotExpr) String()string

typeOrExpr¶

type OrExpr struct {X, YExpr}

An OrExpr represents the expression X || Y.

func (x *OrExpr) Eval(ok func(tagstring)bool)bool

func (x *OrExpr) String()string

typeSyntaxError¶

type SyntaxError struct {Offsetint// byte offset in input where error was detectedErrstring// description of error}

A SyntaxError reports a syntax error in a parsed build expression.

func (e *SyntaxError) Error()string

typeTagExpr¶

type TagExpr struct {Tagstring// for example, “linux” or “cgo”}

A TagExpr is anExpr for the single tag Tag.

func (x *TagExpr) Eval(ok func(tagstring)bool)bool

func (x *TagExpr) String()string