From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html | 88 +++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html (limited to 'devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html') diff --git a/devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html b/devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html new file mode 100644 index 00000000..1a648460 --- /dev/null +++ b/devdocs/go/go%2Fbuild%2Fconstraint%2Findex.html @@ -0,0 +1,88 @@ +

Package constraint

import "go/build/constraint"
Overview
Index

Overview

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.

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.

Index

Package files

expr.go vers.go

func GoVersion 1.21

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.

For example:

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.

For example:

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

func IsGoBuild 1.16

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.

func IsPlusBuild 1.16

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.

func PlusBuildLines 1.16

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.

type AndExpr 1.16

An AndExpr represents the expression X && Y.

type AndExpr struct {
+    X, Y Expr
+}
+

func (*AndExpr) Eval 1.16

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

func (*AndExpr) String 1.16

func (x *AndExpr) String() string

type Expr 1.16

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

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
+}

func Parse 1.16

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.

type NotExpr 1.16

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

type NotExpr struct {
+    X Expr
+}
+

func (*NotExpr) Eval 1.16

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

func (*NotExpr) String 1.16

func (x *NotExpr) String() string

type OrExpr 1.16

An OrExpr represents the expression X || Y.

type OrExpr struct {
+    X, Y Expr
+}
+

func (*OrExpr) Eval 1.16

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

func (*OrExpr) String 1.16

func (x *OrExpr) String() string

type SyntaxError 1.16

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

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

func (*SyntaxError) Error 1.16

func (e *SyntaxError) Error() string

type TagExpr 1.16

A TagExpr is an Expr for the single tag Tag.

type TagExpr struct {
+    Tag string // for example, “linux” or “cgo”
+}
+

func (*TagExpr) Eval 1.16

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

func (*TagExpr) String 1.16

func (x *TagExpr) String() string

+ © Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
+ http://golang.org/pkg/go/build/constraint/ +

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