micro/util/router/compile.go

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package router
// download from https://raw.githubusercontent.com/grpc-ecosystem/grpc-gateway/master/protoc-gen-grpc-gateway/httprule/compile.go
const (
opcodeVersion = 1
)
// Template is a compiled representation of path templates.
type Template struct {
// Version is the version number of the format.
Version int
// OpCodes is a sequence of operations.
OpCodes []int
// Pool is a constant pool
Pool []string
// Verb is a VERB part in the template.
Verb string
// Fields is a list of field paths bound in this template.
Fields []string
// Original template (example: /v1/a_bit_of_everything)
Template string
}
// Compiler compiles utilities representation of path templates into marshallable operations.
// They can be unmarshalled by runtime.NewPattern.
type Compiler interface {
Compile() Template
}
type op struct {
// code is the opcode of the operation
code OpCode
// str is a string operand of the code.
// operand is ignored if str is not empty.
str string
// operand is a numeric operand of the code.
operand int
}
func (w wildcard) compile() []op {
return []op{
{code: OpPush},
}
}
func (w deepWildcard) compile() []op {
return []op{
{code: OpPushM},
}
}
func (l literal) compile() []op {
return []op{
{
code: OpLitPush,
str: string(l),
},
}
}
func (v variable) compile() []op {
var ops []op
for _, s := range v.segments {
ops = append(ops, s.compile()...)
}
ops = append(ops, op{
code: OpConcatN,
operand: len(v.segments),
}, op{
code: OpCapture,
str: v.path,
})
return ops
}
func (t template) Compile() Template {
var rawOps []op
for _, s := range t.segments {
rawOps = append(rawOps, s.compile()...)
}
var (
ops []int
pool []string
fields []string
)
consts := make(map[string]int)
for _, op := range rawOps {
ops = append(ops, int(op.code))
if op.str == "" {
ops = append(ops, op.operand)
} else {
if _, ok := consts[op.str]; !ok {
consts[op.str] = len(pool)
pool = append(pool, op.str)
}
ops = append(ops, consts[op.str])
}
if op.code == OpCapture {
fields = append(fields, op.str)
}
}
return Template{
Version: opcodeVersion,
OpCodes: ops,
Pool: pool,
Verb: t.verb,
Fields: fields,
Template: t.template,
}
}