Add documentation

cmd/config.go

@@ -14,6 +14,7 @@ func init() {
 	config = Config{}
 }
 
+// Config is to store all command line Flags.
 type Config struct {
 	PrimaryKeyPositions  []int
 	ValueColumnPositions []int
@@ -23,32 +24,38 @@ type Config struct {
 	Modifications        string
 }
 
+// GetPrimaryKeys is to return the --primary-key flags as digest.Positions array.
 func (c *Config) GetPrimaryKeys() digest.Positions {
 	if len(c.PrimaryKeyPositions) > 0 {
 		return c.PrimaryKeyPositions
 	}
 	return []int{0}
 }
 
+// GetValueColumns is to return the --value-columns flags as digest.Positions array.
 func (c *Config) GetValueColumns() digest.Positions {
 	if len(c.ValueColumnPositions) > 0 {
 		return c.ValueColumnPositions
 	}
 	return []int{}
 }
 
+// GetBaseReader returns an io.Reader for the base file.
 func (c *Config) GetBaseReader() io.Reader {
 	return getReader(c.Base)
 }
 
+// GetDeltaReader returns an io.Reader for the delta file.
 func (c *Config) GetDeltaReader() io.Reader {
 	return getReader(c.Delta)
 }
 
+// AdditionsWriter gives the output stream for the additions in delta csv.
 func (c *Config) AdditionsWriter() io.WriteCloser {
 	return getWriter(c.Additions)
 }
 
+// ModificationsWriter gives the output stream for the modifications in delta csv.
 func (c *Config) ModificationsWriter() io.WriteCloser {
 	return getWriter(c.Modifications)
 }

pkg/digest/compare.go

@@ -1,5 +1,7 @@
 package digest
 
+// Compare compares two Digest maps and returns the additions and modification
+// keys as arrays.
 func Compare(baseDigest, newDigest map[uint64]uint64) (additions []uint64, modifications []uint64) {
 	maxSize := len(newDigest)
 	additions = make([]uint64, maxSize)

pkg/digest/digest.go

@@ -8,6 +8,7 @@ import (
 	"github.com/cespare/xxhash"
 )
 
+// Separator for CSV. Not configurable for now.
 const Separator = ","
 
 // Digest represents the binding of the key of each csv line
@@ -29,6 +30,8 @@ func CreateDigest(csv []string, pKey Positions, pRow Positions) Digest {
 
 }
 
+// Config represents configurations that can be passed
+// to create a Digest.
 type Config struct {
 	KeyPositions []int
 	Key          Positions
@@ -38,6 +41,7 @@ type Config struct {
 	SourceMap    bool
 }
 
+// NewConfig creates an instance of Config struct.
 func NewConfig(r io.Reader, createSourceMap bool, primaryKey Positions, valueColumns Positions) *Config {
 	return &Config{
 		Reader:    r,
@@ -47,6 +51,9 @@ func NewConfig(r io.Reader, createSourceMap bool, primaryKey Positions, valueCol
 	}
 }
 
+// Create can create a Digest using the Configurations passed.
+// It returns the digest as a map[uint64]uint64.
+// It can also keep track of the Source line.
 func Create(config *Config) (map[uint64]uint64, map[uint64]string, error) {
 	reader := csv.NewReader(config.Reader)
 

pkg/digest/positions.go

@@ -2,8 +2,12 @@ package digest
 
 import "strings"
 
+// Positions represents positions of columns in a CSV array.
 type Positions []int
 
+// MapToValue plucks the values from CSV from
+// their respective positions and concatenates
+// them using Separator as a string.
 func (p Positions) MapToValue(csv []string) string {
 	if p.Length() == 0 {
 		return strings.Join(csv, Separator)
@@ -15,10 +19,13 @@ func (p Positions) MapToValue(csv []string) string {
 	return strings.Join(output, Separator)
 }
 
+// Length returns the size of the Positions array.
 func (p Positions) Length() int {
 	return len([]int(p))
 }
 
+// Items returns the elements of the Positions array
+// as an array of int
 func (p Positions) Items() []int {
 	return []int(p)
 }