build/contraint

原文：https://pkg.go.dev/go/build/constraint@go1.23.0

Package constraint implements parsing and evaluation of build constraint lines. See https://golang.org/cmd/go/#hdr-Build_constraints for documentation about build constraints themselves.

​ Package constraint 实现构建约束行的解析和评估。有关构建约束本身的文档，请参阅 https://golang.org/cmd/go/#hdr-Build_constraints。

This package parses both the original “// +build” syntax and the “//go:build” syntax that was added in Go 1.17. See https://golang.org/design/draft-gobuild for details about the “//go:build” syntax.

​ 此软件包同时解析原始的 “// +build” 语法和 Go 1.17 中添加的 “//go:build” 语法。有关 “//go:build” 语法的详细信息，请参阅 https://golang.org/design/draft-gobuild。

常量

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变量

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函数

func GoVersion <- go1.21.0

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func GoVersion(x Expr) 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.

​ GoVersion 返回给定构建表达式暗示的最低 Go 版本。如果表达式可以在没有任何 Go 版本标记的情况下得到满足，则 GoVersion 返回一个空字符串。

For example:

​ 例如：

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

​ GoVersion 假设任何标记或否定标记都可能独立为真，以便其分析可以是纯粹的结构性，而无需 SAT 求解。“不可能”的子表达式因此可能会影响结果。

For example:

​ 例如：

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

func IsGoBuild

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func IsGoBuild(line string) 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.

​ IsGoBuild 报告文本行是否为 “//go:build” 约束。它只检查文本的前缀，而不是表达式本身的解析。

func IsPlusBuild

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func IsPlusBuild(line string) 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.

​ IsPlusBuild 报告文本行是否为 “// +build” 约束。它只检查文本的前缀，而不是表达式本身的解析。

func PlusBuildLines

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func PlusBuildLines(x Expr) ([]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.

​ PlusBuildLines 返回一个 “// +build” 行序列，该序列评估为构建表达式 x。如果表达式过于复杂，无法直接转换为 “// +build” 行，则 PlusBuildLines 返回一个错误。

类型

type AndExpr

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type AndExpr struct {
	X, Y Expr
}

An AndExpr represents the expression X && Y.

​ AndExpr 表示表达式 X && Y。

(*AndExpr) Eval

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func (x *AndExpr) Eval(ok func(tag string) bool) bool

(*AndExpr) String

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func (x *AndExpr) String() string

type Expr

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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(tag string) 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.

​ Expr 是一个构建标记约束表达式。底层具体类型是 *AndExpr、*OrExpr、*NotExpr 或 *TagExpr。

func Parse

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func Parse(line string) (Expr, error)

Parse parses a single build constraint line of the form “//go:build …” or “// +build …” and returns the corresponding boolean expression.

​ Parse 解析形式为 “//go:build …” 或 “// +build …” 的单个构建约束行，并返回相应的布尔表达式。

type NotExpr

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type NotExpr struct {
	X Expr
}

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

​ NotExpr 表示表达式 !X（X 的否定）。

(*NotExpr) Eval

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func (x *NotExpr) Eval(ok func(tag string) bool) bool

(*NotExpr) String

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func (x *NotExpr) String() string

type OrExpr

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type OrExpr struct {
	X, Y Expr
}

An OrExpr represents the expression X || Y.

​ OrExpr 表示表达式 X || Y。

(*OrExpr) Eval

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func (x *OrExpr) Eval(ok func(tag string) bool) bool

(*OrExpr) String

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func (x *OrExpr) String() string

type SyntaxError

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type SyntaxError struct {
	Offset int    // byte offset in input where error was detected
	Err    string // description of error
}

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

​ SyntaxError 报告解析的构建表达式中的语法错误。

(*SyntaxError) Error

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func (e *SyntaxError) Error() string

type TagExpr

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type TagExpr struct {
	Tag string // for example, "linux" or "cgo"
}

A TagExpr is an Expr for the single tag Tag.

​ TagExpr 是用于单个标记 Tag 的 Expr。

(*TagExpr) Eval

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func (x *TagExpr) Eval(ok func(tag string) bool) bool

(*TagExpr) String

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func (x *TagExpr) String() string