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|
// Package main implements a parser for Thrift files (https://thrift.apache.org/)
//
// It parses namespaces, exceptions, services, structs, consts, typedefs and enums, but is easily
// extensible to more.
//
// It also supports annotations and method throws.
package main
import (
"fmt"
"os"
"strings"
"github.com/alecthomas/kong"
"github.com/alecthomas/repr"
"github.com/alecthomas/participle/v2"
"github.com/alecthomas/participle/v2/lexer"
)
type Namespace struct {
Pos lexer.Position
Language string `"namespace" @Ident`
Namespace string `@Ident ( @"." @Ident )*`
}
type Type struct {
Pos lexer.Position
Name string `@Ident ( @"." @Ident )*`
TypeOne *Type `( "<" @@ ( ","`
TypeTwo *Type ` @@ )? ">" )?`
}
type Annotation struct {
Pos lexer.Position
Key string `@Ident ( @"." @Ident )*`
Value *Literal `( "=" @@ )?`
}
type Field struct {
Pos lexer.Position
ID string `@Number ":"`
Requirement string `@( "optional" | "required" )?`
Type *Type `@@`
Name string `@Ident`
Default *Literal `( "=" @@ )?`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )? ";"?`
}
type Exception struct {
Pos lexer.Position
Name string `"exception" @Ident "{"`
Fields []*Field `@@ @@* "}"`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
}
type Struct struct {
Pos lexer.Position
Union bool `( "struct" | @"union" )`
Name string `@Ident "{"`
Fields []*Field `@@* "}"`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
}
type Argument struct {
Pos lexer.Position
ID string `@Number ":"`
Type *Type `@@`
Name string `@Ident`
}
type Throw struct {
Pos lexer.Position
ID string `@Number ":"`
Type *Type `@@`
Name string `@Ident`
}
type Method struct {
Pos lexer.Position
ReturnType *Type `@@`
Name string `@Ident`
Arguments []*Argument `"(" ( @@ ( "," @@ )* )? ")"`
Throws []*Throw `( "throws" "(" @@ ( "," @@ )* ")" )?`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
}
type Service struct {
Pos lexer.Position
Name string `"service" @Ident`
Extends string `( "extends" @Ident ( @"." @Ident )* )?`
Methods []*Method `"{" ( @@ ";"? )* "}"`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
}
// Literal is a "union" type, where only one matching value will be present.
type Literal struct {
Pos lexer.Position
Str *string ` @String`
Number *float64 `| @Number`
Bool *string `| @( "true" | "false" )`
Reference *string `| @Ident ( @"." @Ident )*`
Minus *Literal `| "-" @@`
List []*Literal `| "[" ( @@ ","? )* "]"`
Map []*MapItem `| "{" ( @@ ","? )* "}"`
}
func (l *Literal) GoString() string {
switch {
case l.Str != nil:
return fmt.Sprintf("%q", *l.Str)
case l.Number != nil:
return fmt.Sprintf("%v", *l.Number)
case l.Bool != nil:
return fmt.Sprintf("%v", *l.Bool)
case l.Reference != nil:
return fmt.Sprintf("%s", *l.Reference)
case l.Minus != nil:
return fmt.Sprintf("-%v", l.Minus)
case l.List != nil:
parts := []string{}
for _, e := range l.List {
parts = append(parts, e.GoString())
}
return fmt.Sprintf("[%s]", strings.Join(parts, ", "))
case l.Map != nil:
parts := []string{}
for _, e := range l.Map {
parts = append(parts, e.GoString())
}
return fmt.Sprintf("{%s}", strings.Join(parts, ", "))
}
panic("unsupported?")
}
type MapItem struct {
Pos lexer.Position
Key *Literal `@@ ":"`
Value *Literal `@@`
}
func (m *MapItem) GoString() string {
return fmt.Sprintf("%v: %v", m.Key, m.Value)
}
type Case struct {
Pos lexer.Position
Name string `@Ident`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
Value *Literal `( "=" @@ )? ( "," | ";" )?`
}
type Enum struct {
Pos lexer.Position
Name string `"enum" @Ident "{"`
Cases []*Case `@@* "}"`
Annotations []*Annotation `( "(" @@ ( "," @@ )* ")" )?`
}
type Typedef struct {
Pos lexer.Position
Type *Type `"typedef" @@`
Name string `@Ident`
}
type Const struct {
Pos lexer.Position
Type *Type `"const" @@`
Name string `@Ident`
Value *Literal `"=" @@ ";"?`
}
type Entry struct {
Pos lexer.Position
Includes []string ` "include" @String`
Namespaces []*Namespace `| @@`
Structs []*Struct `| @@`
Exceptions []*Exception `| @@`
Services []*Service `| @@`
Enums []*Enum `| @@`
Typedefs []*Typedef `| @@`
Consts []*Const `| @@`
}
// Thrift files consist of a set of top-level directives and definitions.
//
// The grammar
type Thrift struct {
Pos lexer.Position
Entries []*Entry `@@*`
}
var (
def = lexer.MustSimple([]lexer.SimpleRule{
{"Number", `\d+`},
{"Ident", `\w+`},
{"String", `"[^"]*"`},
{"Whitespace", `\s+`},
{"Punct", `[,.<>(){}=:]`},
{"Comment", `//.*`},
})
parser = participle.MustBuild[Thrift](
participle.Lexer(def),
participle.Unquote(),
participle.Elide("Whitespace"),
)
)
func main() {
var cli struct {
Gen bool `help:"Generate lexer."`
Files []string `help:"Thrift files."`
}
ctx := kong.Parse(&cli)
for _, file := range cli.Files {
r, err := os.Open(file)
ctx.FatalIfErrorf(err, "")
thrift, err := parser.Parse("", r)
ctx.FatalIfErrorf(err, "")
repr.Println(thrift)
}
}
|
