Add 'check' command with support for indent style/size, trailing whitespace.

bin/run-check

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+go run main.go check editorconfig/tests/

editorconfig/check_command.go

@@ -0,0 +1,51 @@
+package editorconfig
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/codegangsta/cli"
+	"os"
+	"strconv"
+)
+
+func CheckCommand(c *cli.Context) error {
+	files, err := FindSourceFiles(c.Args())
+	if err != nil {
+		return err
+	}
+
+	configs := FindConfigFiles(files)
+
+	for _, f := range files {
+		fh, err := os.Open(f)
+		if err != nil {
+			ExitBecauseOfInternalError("Could not read file: " + f)
+		}
+
+		// @todo - add "full file checkers" for end_of_line, insert_final_newline and charset.
+
+		scanner := bufio.NewScanner(fh)
+		rules := GetRulesToApplyToSourcePath(f, configs)
+
+		lineNo := 0
+		for scanner.Scan() {
+			line := scanner.Text()
+			lineNo++
+
+			for ruleName, ruleValue := range rules {
+				if lineCheckers[ruleName] == nil {
+					continue
+				}
+
+				result := lineCheckers[ruleName](ruleValue, line)
+				if !result.isOk {
+					fmt.Println(f + ": line " + strconv.Itoa(lineNo) + ": " + ruleName + ": " + result.messageIfNotOk)
+					// Don't show more than 1 error per line.
+					break
+				}
+			}
+		}
+	}
+
+	return nil
+}

editorconfig/cli.go

@@ -22,6 +22,11 @@ func CreateCliApp() *cli.App {
 			Usage:  "List rules that match a given file",
 			Action: RulesCommand,
 		},
+		{
+			Name:   "check",
+			Usage:  "Validate files",
+			Action: CheckCommand,
+		},
 	}
 
 	return app