fstest.go

package main

import ( "bufio"; "fmt"; "io"; "log"; "os"; "regexp"; )

/*
real	0m0.026s
user	0m0.019s
sys	0m0.006s
*/
func test1() {
    fileContent, err := io.ReadFile( "data.txt" );
    if err != nil {
        log.Stderr( err );
        return;
    }
    fmt.Printf("Read %v characters in test 1.\n", len(fileContent) );
}

/* 
real	0m0.029s
user	0m0.022s
sys	0m0.006s
*/
func test2() {
    fileObj, err := os.Open( "data.txt", os.O_RDONLY, 0666 );
    if err != nil {
        log.Stderr( err );
        return;
    }
    r := bufio.NewReader( fileObj );
    
    charCount := 0;
    for {
        line, err := r.ReadString('\n');
        if err == os.EOF {
            fmt.Printf("Read %v characters in test 2.\n", charCount );
            return;
        }
        if err != nil {
            log.Stderr( err );
            return;
        }
        
        charCount += len(line);
    }
}

/*
real	0m0.176s
user	0m0.168s
sys	0m0.007s
*/
func test3() {
    fileObj, err := os.Open( "data.txt", os.O_RDONLY, 0666 );
    if err != nil {
        log.Stderr( err );
        return;
    }
    r := bufio.NewReader( fileObj );
    matcher := regexp.MustCompile( "H[a|b][m|n]let" );
    
    charCount := 0;
    lineCount := 0;
    for {
        line, err := r.ReadString('\n');
        lineCount++;
        if err == os.EOF {
            fmt.Printf("Read %v characters in test 3.\n", charCount );
            return;
        }
        if err != nil {
            log.Stderr( err );
            return;
        }
        
        if matcher.MatchString(line) {
            fmt.Printf("Matched at %v.\n", lineCount );
        }
        charCount += len(line);
    }
}

func main() {
    //test1();
    //test2();
    test3();
}