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package runtime
import (
"errors"
"fmt"
"strings"
"github.com/grpc-ecosystem/grpc-gateway/utilities"
"google.golang.org/grpc/grpclog"
)
var (
// ErrNotMatch indicates that the given HTTP request path does not match to the pattern.
ErrNotMatch = errors.New("not match to the path pattern")
// ErrInvalidPattern indicates that the given definition of Pattern is not valid.
ErrInvalidPattern = errors.New("invalid pattern")
)
type op struct {
code utilities.OpCode
operand int
}
// Pattern is a template pattern of http request paths defined in github.com/googleapis/googleapis/google/api/http.proto.
type Pattern struct {
// ops is a list of operations
ops []op
// pool is a constant pool indexed by the operands or vars.
pool []string
// vars is a list of variables names to be bound by this pattern
vars []string
// stacksize is the max depth of the stack
stacksize int
// tailLen is the length of the fixed-size segments after a deep wildcard
tailLen int
// verb is the VERB part of the path pattern. It is empty if the pattern does not have VERB part.
verb string
// assumeColonVerb indicates whether a path suffix after a final
// colon may only be interpreted as a verb.
assumeColonVerb bool
}
type patternOptions struct {
assumeColonVerb bool
}
// PatternOpt is an option for creating Patterns.
type PatternOpt func(*patternOptions)
// NewPattern returns a new Pattern from the given definition values.
// "ops" is a sequence of op codes. "pool" is a constant pool.
// "verb" is the verb part of the pattern. It is empty if the pattern does not have the part.
// "version" must be 1 for now.
// It returns an error if the given definition is invalid.
func NewPattern(version int, ops []int, pool []string, verb string, opts ...PatternOpt) (Pattern, error) {
options := patternOptions{
assumeColonVerb: true,
}
for _, o := range opts {
o(&options)
}
if version != 1 {
grpclog.Infof("unsupported version: %d", version)
return Pattern{}, ErrInvalidPattern
}
l := len(ops)
if l%2 != 0 {
grpclog.Infof("odd number of ops codes: %d", l)
return Pattern{}, ErrInvalidPattern
}
var (
typedOps []op
stack, maxstack int
tailLen int
pushMSeen bool
vars []string
)
for i := 0; i < l; i += 2 {
op := op{code: utilities.OpCode(ops[i]), operand: ops[i+1]}
switch op.code {
case utilities.OpNop:
continue
case utilities.OpPush:
if pushMSeen {
tailLen++
}
stack++
case utilities.OpPushM:
if pushMSeen {
grpclog.Infof("pushM appears twice")
return Pattern{}, ErrInvalidPattern
}
pushMSeen = true
stack++
case utilities.OpLitPush:
if op.operand < 0 || len(pool) <= op.operand {
grpclog.Infof("negative literal index: %d", op.operand)
return Pattern{}, ErrInvalidPattern
}
if pushMSeen {
tailLen++
}
stack++
case utilities.OpConcatN:
if op.operand <= 0 {
grpclog.Infof("negative concat size: %d", op.operand)
return Pattern{}, ErrInvalidPattern
}
stack -= op.operand
if stack < 0 {
grpclog.Print("stack underflow")
return Pattern{}, ErrInvalidPattern
}
stack++
case utilities.OpCapture:
if op.operand < 0 || len(pool) <= op.operand {
grpclog.Infof("variable name index out of bound: %d", op.operand)
return Pattern{}, ErrInvalidPattern
}
v := pool[op.operand]
op.operand = len(vars)
vars = append(vars, v)
stack--
if stack < 0 {
grpclog.Infof("stack underflow")
return Pattern{}, ErrInvalidPattern
}
default:
grpclog.Infof("invalid opcode: %d", op.code)
return Pattern{}, ErrInvalidPattern
}
if maxstack < stack {
maxstack = stack
}
typedOps = append(typedOps, op)
}
return Pattern{
ops: typedOps,
pool: pool,
vars: vars,
stacksize: maxstack,
tailLen: tailLen,
verb: verb,
assumeColonVerb: options.assumeColonVerb,
}, nil
}
// MustPattern is a helper function which makes it easier to call NewPattern in variable initialization.
func MustPattern(p Pattern, err error) Pattern {
if err != nil {
grpclog.Fatalf("Pattern initialization failed: %v", err)
}
return p
}
// Match examines components if it matches to the Pattern.
// If it matches, the function returns a mapping from field paths to their captured values.
// If otherwise, the function returns an error.
func (p Pattern) Match(components []string, verb string) (map[string]string, error) {
if p.verb != verb {
if p.assumeColonVerb || p.verb != "" {
return nil, ErrNotMatch
}
if len(components) == 0 {
components = []string{":" + verb}
} else {
components = append([]string{}, components...)
components[len(components)-1] += ":" + verb
}
verb = ""
}
var pos int
stack := make([]string, 0, p.stacksize)
captured := make([]string, len(p.vars))
l := len(components)
for _, op := range p.ops {
switch op.code {
case utilities.OpNop:
continue
case utilities.OpPush, utilities.OpLitPush:
if pos >= l {
return nil, ErrNotMatch
}
c := components[pos]
if op.code == utilities.OpLitPush {
if lit := p.pool[op.operand]; c != lit {
return nil, ErrNotMatch
}
}
stack = append(stack, c)
pos++
case utilities.OpPushM:
end := len(components)
if end < pos+p.tailLen {
return nil, ErrNotMatch
}
end -= p.tailLen
stack = append(stack, strings.Join(components[pos:end], "/"))
pos = end
case utilities.OpConcatN:
n := op.operand
l := len(stack) - n
stack = append(stack[:l], strings.Join(stack[l:], "/"))
case utilities.OpCapture:
n := len(stack) - 1
captured[op.operand] = stack[n]
stack = stack[:n]
}
}
if pos < l {
return nil, ErrNotMatch
}
bindings := make(map[string]string)
for i, val := range captured {
bindings[p.vars[i]] = val
}
return bindings, nil
}
// Verb returns the verb part of the Pattern.
func (p Pattern) Verb() string { return p.verb }
func (p Pattern) String() string {
var stack []string
for _, op := range p.ops {
switch op.code {
case utilities.OpNop:
continue
case utilities.OpPush:
stack = append(stack, "*")
case utilities.OpLitPush:
stack = append(stack, p.pool[op.operand])
case utilities.OpPushM:
stack = append(stack, "**")
case utilities.OpConcatN:
n := op.operand
l := len(stack) - n
stack = append(stack[:l], strings.Join(stack[l:], "/"))
case utilities.OpCapture:
n := len(stack) - 1
stack[n] = fmt.Sprintf("{%s=%s}", p.vars[op.operand], stack[n])
}
}
segs := strings.Join(stack, "/")
if p.verb != "" {
return fmt.Sprintf("/%s:%s", segs, p.verb)
}
return "/" + segs
}
// AssumeColonVerbOpt indicates whether a path suffix after a final
// colon may only be interpreted as a verb.
func AssumeColonVerbOpt(val bool) PatternOpt {
return PatternOpt(func(o *patternOptions) {
o.assumeColonVerb = val
})
}
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