dhamidi/example.esh

## example.esh
<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title><%= "$TITLE" %></title>
    <script type="text/javascript" src="jquery.js"></script>
  </head>
  <body>
    <p>It's alive!</p>
    <ul>
      <%- for i in 1 2 3; do %>
      <li><%= "$i" %></li>
      <%- done %>
    </ul>
  </body>
</html>

## example.html
<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script type="text/javascript" src="jquery.js"></script>
  </head>
  <body>
    <p>It's alive!</p>
    <ul>
      <li>1</li>
      <li>2</li>
      <li>3</li>
    </ul>
  </body>
</html>

## example.sh
printf "%s\n" '<!doctype html>'
printf "%s\n" '<html>'
printf "%s\n" '  <head>'
printf "%s\n" '    <meta charset="utf-8">'
printf "%s" '    <title>'
printf "%s"  "$TITLE"
printf "%s\n" '</title>'
printf "%s\n" '    <script type="text/javascript" src="jquery.js"></script>'
printf "%s\n" '  </head>'
printf "%s\n" '  <body>'
printf "%s\n" '    <p>It'\''s alive!</p>'
printf "%s\n" '    <ul>'
printf "%s" ''
 for i in 1 2 3; do
printf "%s" '      <li>'
printf "%s"  "$i"
printf "%s\n" '</li>'
printf "%s" ''
 done
printf "%s\n" '    </ul>'
printf "%s\n" '  </body>'
printf "%s\n" '</html>'

## template.awk
#! awk -f
BEGIN {
    template_re = "<%[-= %][^%]+ %>"
    template_system_prefix["="] = "printf \"%s\" "
}

function shell_quote(text) {
    gsub(/'/, "'\\''", text)
    return sprintf("'%s'", text)
}

function emit_text_1(text, newline) {
    printf("printf \"%%s%s\" %s\n", (newline ? "\\n" : ""), shell_quote(text))
}

function emit_text(text) {
    emit_text_1(text, 0)
}

function emit_text_nl(text) {
    emit_text_1(text, 1)
}

function emit_code(prefix, code) {
    if (length(prefix) + length(code) > 0)
        printf "%s%s\n", prefix, code
}

function compile_fragment(text) {
    # everything up to <%
    before_match = substr(text, 1, RSTART - 1)
    # skip over <%, return [-= ]
    prefix = substr(text, RSTART + 2, 1)
    # skip over prefix and exclude postix ("%>")
    command = substr(text, RSTART + 3, RLENGTH - 5)
    # the rest of the line
    after_match = substr(text, RSTART + RLENGTH)

    if (prefix == "-") {
        sub(/^[[:blank:]]+/, "", before_match)
    } else if (prefix == "%") {
        before_match = before_match "<%" command
        command = ""
        after_match = "%>" after_match
    }

    emit_text(before_match)
    emit_code(template_system_prefix[prefix], command)
    return after_match
}

$0 ~ template_re {
    text = $0
    found = match(text, template_re)

    while (found) {
        text = compile_fragment(text)
        found = match(text, template_re)
    }

    if (length(text) > 0)
        emit_text_nl(text)
}

$0 !~ template_re {
    emit_text_nl($0)
}
	<!doctype html>
	<html>
	<head>
	<meta charset="utf-8">
	<title><%= "$TITLE" %></title>
	<script type="text/javascript" src="jquery.js"></script>
	</head>
	<body>
	<p>It's alive!</p>
	<ul>
	<%- for i in 1 2 3; do %>
	<li><%= "$i" %></li>
	<%- done %>
	</ul>
	</body>
	</html>
	printf "%s\n" '<!doctype html>'
	printf "%s\n" '<html>'
	printf "%s\n" ' <head>'
	printf "%s\n" ' <meta charset="utf-8">'
	printf "%s" ' <title>'
	printf "%s" "$TITLE"
	printf "%s\n" '</title>'
	printf "%s\n" ' <script type="text/javascript" src="jquery.js"></script>'
	printf "%s\n" ' </head>'
	printf "%s\n" ' <body>'
	printf "%s\n" ' <p>It'\''s alive!</p>'
	printf "%s\n" ' <ul>'
	printf "%s" ''
	for i in 1 2 3; do
	printf "%s" ' <li>'
	printf "%s" "$i"
	printf "%s\n" '</li>'
	printf "%s" ''
	done
	printf "%s\n" ' </ul>'
	printf "%s\n" ' </body>'
	printf "%s\n" '</html>'
	#! awk -f
	BEGIN {
	template_re = "<%[-= %][^%]+ %>"
	template_system_prefix["="] = "printf \"%s\" "
	}

	function shell_quote(text) {
	gsub(/'/, "'\\''", text)
	return sprintf("'%s'", text)
	}

	function emit_text_1(text, newline) {
	printf("printf \"%%s%s\" %s\n", (newline ? "\\n" : ""), shell_quote(text))
	}

	function emit_text(text) {
	emit_text_1(text, 0)
	}

	function emit_text_nl(text) {
	emit_text_1(text, 1)
	}

	function emit_code(prefix, code) {
	if (length(prefix) + length(code) > 0)
	printf "%s%s\n", prefix, code
	}

	function compile_fragment(text) {
	# everything up to <%
	before_match = substr(text, 1, RSTART - 1)
	# skip over <%, return [-= ]
	prefix = substr(text, RSTART + 2, 1)
	# skip over prefix and exclude postix ("%>")
	command = substr(text, RSTART + 3, RLENGTH - 5)
	# the rest of the line
	after_match = substr(text, RSTART + RLENGTH)

	if (prefix == "-") {
	sub(/^[[:blank:]]+/, "", before_match)
	} else if (prefix == "%") {
	before_match = before_match "<%" command
	command = ""
	after_match = "%>" after_match
	}

	emit_text(before_match)
	emit_code(template_system_prefix[prefix], command)
	return after_match
	}

	$0 ~ template_re {
	text = $0
	found = match(text, template_re)

	while (found) {
	text = compile_fragment(text)
	found = match(text, template_re)
	}

	if (length(text) > 0)
	emit_text_nl(text)
	}

	$0 !~ template_re {
	emit_text_nl($0)
	}