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|
// grammar of the config file
//
// Notes: We parse exactly three modules ("input", "filter", "output")
// in our configuration. Each module consists of two name-object pairs
// that are nested. We don't want to allow limitless recursion here.
//
// config = mainmodule mainmodule mainmodule
// mainmodule = name '{' module+ '}'
// module = name object
// name = 'input' | 'filter' | 'output' | etc.
// object = '{' keyvalue* '}'
// keyvalue = statement '=>' value
// statement = name | if
// value = literal | '[' literal ']'
// literal = '"' name '"'
package conf
import (
"fmt"
"io"
"os"
"github.com/Shugyousha/stasher/registry"
)
// Having a Config to Manager function could be nice? Or we could just
// return a Manager from here which may be even better...
type Config struct {
}
type parser struct {
s scanner
last token
cur token
}
type moduledesc struct {
name string
keyvalues map[string]string
}
func newParser(s *scanner) *parser {
p := &parser{
s: *s,
}
return p
}
func NewConfig(r io.Reader) *Config {
p := newParser(newScanner(r))
p.startparsing()
return &Config{}
}
func (p *parser) startparsing() {
inputmdescs := p.mainmodule("input")
fmt.Fprintf(os.Stderr, "input moduledescs: %#v\n", inputmdescs)
for _, idesc := range inputmdescs {
inputnewfunc, ok := registry.Inputregistry[idesc.name]
if !ok {
fmt.Fprintf(os.Stderr, "input module is not known: %q\n", idesc.name)
}
inputnewfunc(nil)
}
filtermdescs := p.mainmodule("filter")
fmt.Fprintf(os.Stderr, "filter moduledescs: %#v\n", filtermdescs)
for _, fdesc := range filtermdescs {
filternewfunc, ok := registry.Filterregistry[fdesc.name]
if !ok {
fmt.Fprintf(os.Stderr, "filter module is not known: %q\n", fdesc.name)
}
filternewfunc(nil)
}
outputmdescs := p.mainmodule("output")
fmt.Fprintf(os.Stderr, "output moduledescs: %#v\n", outputmdescs)
for _, odesc := range outputmdescs {
filternewfunc, ok := registry.Outputregistry[odesc.name]
if !ok {
fmt.Fprintf(os.Stderr, "output module is not known: %q\n", odesc.name)
}
filternewfunc(nil)
}
}
func (p *parser) advanceOneToken(place string) {
var err error
p.last = p.cur
p.cur, err = p.s.Scan()
if err != nil {
fmt.Fprintf(os.Stderr, "Error: tokentype: %v, token: %q, err: %v\n", p.cur.Type, p.cur.Lit, err)
}
fmt.Fprintf(os.Stderr, "tokentype: %v, token: %q\n", p.cur.Type, p.cur.Lit)
}
func (p *parser) mainmodule(firstname string) []moduledesc {
var moduledescs []moduledesc
md := moduledesc{keyvalues: make(map[string]string)}
p.advanceOneToken("mainmodule")
if p.cur.Lit != firstname {
fmt.Fprintf(os.Stderr, "error when parsing module. We were expecting name %q but got %q at line %d offset %d.\n", firstname, p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
p.advanceOneToken("mainmodule")
if p.cur.Type != ObjectOpen {
fmt.Fprintf(os.Stderr, "error when parsing module. We were expecting an opening bracket but got %q at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
for {
p.advanceOneToken("more modules")
if p.cur.Type != Name {
if p.cur.Lit[0] == '}' {
break
}
fmt.Fprintf(os.Stderr, "error when parsing module. We were expecting either a name or the end of the module but got %q at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
md.name = p.cur.Lit
md.keyvalues = p.object(md.keyvalues)
moduledescs = append(moduledescs, md)
md = moduledesc{keyvalues: make(map[string]string)}
}
return moduledescs
}
func (p *parser) object(kv map[string]string) map[string]string {
var more bool
p.advanceOneToken("object")
if p.cur.Lit[0] != '{' {
fmt.Fprintf(os.Stderr, "error when parsing object. Was expecting an opening bracket but got %s at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
// hack to deal with case where there is no white space between
// the delimiters.
if p.cur.Lit == "{}" {
return kv
}
for {
more, kv = p.keyvalue(kv)
if !more {
break
}
}
return kv
}
func (p *parser) keyvalue(kv map[string]string) (bool, map[string]string) {
p.advanceOneToken("keyvalue")
fmt.Fprintf(os.Stderr, "keyvalue: tokentype: %v, token: %q\n", p.cur.Type, p.cur.Lit)
if p.cur.Type != Literal && p.cur.Type != Name {
fmt.Fprintf(os.Stderr, "error when parsing keyvalue. Was expecting a name or a literal but got %q at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
lhs := p.cur.Lit
p.advanceOneToken("keyvalue")
if p.cur.Lit != "=>" {
fmt.Fprintf(os.Stderr, "error when parsing keyvalue. Was expecting a '=>' but got %q at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
p.advanceOneToken("keyvalue")
if p.cur.Type != Literal && p.cur.Type != Name {
fmt.Fprintf(os.Stderr, "error when parsing keyvalue. Was expecting a literal or a name but got %q at line %d offset %d.\n", p.cur.Lit, p.cur.LineNr, p.cur.Offset)
}
kv[lhs] = p.cur.Lit
tok, err := p.s.Peek()
if err != nil {
fmt.Fprintf(os.Stderr, "error when parsing keyvalue. Got an error when checking if there are more keyvalues: %v.\n", err)
return false, kv
}
fmt.Fprintf(os.Stderr, "peeked %q (type %v) at line %d offset %d.\n", tok.Lit, tok.Type, tok.LineNr, tok.Offset)
if tok.Type == ObjectClose {
p.advanceOneToken("keyvaluelast")
return false, kv
}
return true, kv
}
|
