Add new lexer.

deps.json

@@ -9,6 +9,11 @@
         "version": "8a44ce0c654efd505418bb2c341cb9b797020583",
         "type": "git"
     },
+    "goconvey": {
+        "repo": "github.com/smartystreets/goconvey/convey",
+        "version": "master",
+        "type": "git"
+    },
     "gocql": {
         "repo": "tux21b.org/v1/gocql",
         "version": "44eda643c1ae69e866e491b1c935c5b22e42350e",

query/parser.go

@@ -3,9 +3,104 @@ package query
 import (
 	"encoding/json"
 	"errors"
+	"log"
 	"pilosa/db"
+	"github.com/davecgh/go-spew/spew"
 )
 
+const (
+	TYPE_FUNC = iota
+	TYPE_LP = iota
+	TYPE_RP = iota
+	TYPE_ID = iota
+)
+
+type Token struct {
+	Text string
+	Type int
+}
+
+type statefn func(lexer *Lexer) statefn
+
+type Lexer struct {
+	text string
+	pos int
+	start int
+	state int
+	ch chan Token
+}
+
+func (lexer *Lexer) emit(typ int) {
+	lexer.ch <- Token{lexer.text[lexer.start:lexer.pos], typ}
+	lexer.start = lexer.pos
+}
+
+func (lexer *Lexer) accept(char uint8) error {
+	for {
+		if lexer.text[lexer.pos] == char {
+			return nil
+		}
+		lexer.pos += 1
+		if lexer.pos > len(lexer.text) {
+			return errors.New("Parse error, expecting " + string(char))
+		}
+	}
+}
+
+func stateFunc(lexer *Lexer) statefn {
+	err := lexer.accept('(')
+	if err != nil {
+		log.Fatal(err)
+	}
+	lexer.emit(TYPE_FUNC)
+	return stateLP
+}
+
+func stateLP(lexer *Lexer) statefn {
+	lexer.pos += 1
+	lexer.emit(TYPE_LP)
+	return stateID
+}
+
+func stateID(lexer *Lexer) statefn {
+	err := lexer.accept(')')
+	if err != nil {
+		log.Fatal(err)
+	}
+	lexer.emit(TYPE_ID)
+	return stateRP
+}
+
+func stateRP(lexer *Lexer) statefn {
+	lexer.pos += 1
+	lexer.emit(TYPE_RP)
+	close(lexer.ch)
+	return nil
+}
+
+func (lexer *Lexer) Lex() []Token{
+	tokens := make([]Token, 0)
+	state := stateFunc
+	go func () {
+		for {
+			state = state(lexer)
+			if state == nil {
+				return
+			}
+		}
+	}()
+	for t := range lexer.ch {
+		spew.Dump(t)
+		tokens = append(tokens, t)
+	}
+	return tokens
+}
+
+func Lex(input string) []Token {
+	lexer := Lexer{input, 0, 0, TYPE_FUNC, make(chan Token)}
+	return lexer.Lex()
+}
+
 var InvalidQueryError = errors.New("Invalid query format.")
 
 type QueryParser struct {

query/parser_test.go

@@ -0,0 +1,21 @@
+package query
+
+import (
+    "testing"
+    . "github.com/smartystreets/goconvey/convey"
+)
+
+func TestParser(t *testing.T) {
+        Convey("Basic parsing", t, func() {
+                tokens := Lex("get(10)")
+                So(len(tokens), ShouldEqual, 4)
+                So(tokens[0].Text, ShouldEqual, "get")
+                So(tokens[0].Type, ShouldEqual, TYPE_FUNC)
+                So(tokens[1].Text, ShouldEqual, "(")
+                So(tokens[1].Type, ShouldEqual, TYPE_LP)
+                So(tokens[2].Text, ShouldEqual, "10")
+                So(tokens[2].Type, ShouldEqual, TYPE_ID)
+                So(tokens[3].Text, ShouldEqual, ")")
+                So(tokens[3].Type, ShouldEqual, TYPE_RP)
+        })
+}