From b6b081b7041ae4a1af79bef096e8c7eb2e4b4afc Mon Sep 17 00:00:00 2001
From: letusfly85 <letusfly95@gmail.com>
Date: Wed, 10 Feb 2016 16:21:07 +0900
Subject: [PATCH 1/2] add sample code

---
 main.go         | 21 +++++++++++++++++++++
 parser.go       |  2 +-
 parser_test.go  |  2 +-
 scanner.go      |  2 +-
 scanner_test.go |  2 +-
 token.go        |  2 +-
 6 files changed, 26 insertions(+), 5 deletions(-)
 create mode 100644 main.go

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..ea18a7d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,21 @@
+package main
+
+import "strings"
+
+func main() {
+	query := "select * from my_table"
+	println(query)
+	r := strings.NewReader(query)
+
+	parser := NewParser(r)
+
+	stmt, err := parser.Parse()
+	if err != nil {
+		println(err.Error())
+	}
+
+	println(stmt.TableName)
+	for _, field := range stmt.Fields {
+		println(field)
+	}
+}
diff --git a/parser.go b/parser.go
index e68a052..aebd7bf 100644
--- a/parser.go
+++ b/parser.go
@@ -1,4 +1,4 @@
-package sql
+package main
 
 import (
 	"fmt"
diff --git a/parser_test.go b/parser_test.go
index f50c402..cb60f5b 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -1,4 +1,4 @@
-package sql_test
+package main
 
 import (
 	"reflect"
diff --git a/scanner.go b/scanner.go
index 53a1f1f..c393de1 100644
--- a/scanner.go
+++ b/scanner.go
@@ -1,4 +1,4 @@
-package sql
+package main
 
 import (
 	"bufio"
diff --git a/scanner_test.go b/scanner_test.go
index 78cfa49..dedeed7 100644
--- a/scanner_test.go
+++ b/scanner_test.go
@@ -1,4 +1,4 @@
-package sql_test
+package main
 
 import (
 	"strings"
diff --git a/token.go b/token.go
index c375a69..0253829 100644
--- a/token.go
+++ b/token.go
@@ -1,4 +1,4 @@
-package sql
+package main
 
 // Token represents a lexical token.
 type Token int

From 21cfdf9478297a9e1874ce670108bf3f5d556ecf Mon Sep 17 00:00:00 2001
From: letusfly85 <letusfly95@gmail.com>
Date: Thu, 11 Feb 2016 13:46:46 +0900
Subject: [PATCH 2/2] add simple  pattern

---
 main.go    |  5 ++++-
 parser.go  | 32 ++++++++++++++++++++++++++++++--
 scanner.go | 17 ++++++++++++++++-
 token.go   |  3 +++
 4 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/main.go b/main.go
index ea18a7d..a39c720 100644
--- a/main.go
+++ b/main.go
@@ -3,7 +3,7 @@ package main
 import "strings"
 
 func main() {
-	query := "select * from my_table"
+	query := "select id, name from employees where department_id = 3 and salary > 10"
 	println(query)
 	r := strings.NewReader(query)
 
@@ -18,4 +18,7 @@ func main() {
 	for _, field := range stmt.Fields {
 		println(field)
 	}
+	for _, condition := range stmt.Conditions {
+		println(condition)
+	}
 }
diff --git a/parser.go b/parser.go
index aebd7bf..0b2dd13 100644
--- a/parser.go
+++ b/parser.go
@@ -7,8 +7,9 @@ import (
 
 // SelectStatement represents a SQL SELECT statement.
 type SelectStatement struct {
-	Fields    []string
-	TableName string
+	Fields     []string
+	TableName  string
+	Conditions []string
 }
 
 // Parser represents a parser.
@@ -63,6 +64,33 @@ func (p *Parser) Parse() (*SelectStatement, error) {
 	}
 	stmt.TableName = lit
 
+	// Next we should see the "WHERE" keyword.
+	if tok, lit := p.scanIgnoreWhitespace(); tok != WHERE {
+		return nil, fmt.Errorf("found %q, expected WHERE", lit)
+	}
+
+	// Next we should loop over all our and delimited conditions.
+	condition := ""
+	for {
+		// Read a field.
+		_, lit := p.scanIgnoreWhitespace()
+		condition += lit
+
+		if tok, lit := p.scanIgnoreWhitespace(); tok == AND {
+			stmt.Conditions = append(stmt.Conditions, condition)
+			condition = ""
+		} else {
+			if tok == EOF {
+				stmt.Conditions = append(stmt.Conditions, condition)
+				p.unscan()
+				break
+			} else {
+				condition += lit
+			}
+
+		}
+	}
+
 	// Return the successfully parsed statement.
 	return stmt, nil
 }
diff --git a/scanner.go b/scanner.go
index c393de1..203d372 100644
--- a/scanner.go
+++ b/scanner.go
@@ -35,6 +35,12 @@ func (s *Scanner) Scan() (tok Token, lit string) {
 
 	// Otherwise read the individual character.
 	switch ch {
+	case '=':
+		return OPER, string(ch)
+	case '>':
+		return OPER, string(ch)
+	case '<':
+		return OPER, string(ch)
 	case eof:
 		return EOF, ""
 	case '*':
@@ -93,6 +99,10 @@ func (s *Scanner) scanIdent() (tok Token, lit string) {
 		return SELECT, buf.String()
 	case "FROM":
 		return FROM, buf.String()
+	case "WHERE":
+		return WHERE, buf.String()
+	case "AND":
+		return AND, buf.String()
 	}
 
 	// Otherwise return as a regular identifier.
@@ -116,10 +126,15 @@ func (s *Scanner) unread() { _ = s.r.UnreadRune() }
 func isWhitespace(ch rune) bool { return ch == ' ' || ch == '\t' || ch == '\n' }
 
 // isLetter returns true if the rune is a letter.
-func isLetter(ch rune) bool { return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') }
+func isLetter(ch rune) bool {
+	return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') //|| isOpers(ch)
+}
 
 // isDigit returns true if the rune is a digit.
 func isDigit(ch rune) bool { return (ch >= '0' && ch <= '9') }
 
+// isOpers returns true if the rune is a digit.
+func isOpers(ch rune) bool { return ch == '=' || ch == '>' || ch == '<' }
+
 // eof represents a marker rune for the end of the reader.
 var eof = rune(0)
diff --git a/token.go b/token.go
index 0253829..ea05133 100644
--- a/token.go
+++ b/token.go
@@ -19,4 +19,7 @@ const (
 	// Keywords
 	SELECT
 	FROM
+	WHERE
+	AND // and
+	OPER
 )