Created
December 18, 2013 08:16
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ERB-like template processor in POSIX AWK.
Usage: ./template.awk < input.esh | sh > output
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| <!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> |
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| <!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> |
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| 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>' |
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| #! 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) | |
| } |
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