Added QSE_AWK_TOLERANT
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@ -4,16 +4,18 @@
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- @ref awk_intro "INTRODUCTION"
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- @ref awk_lang "AWK LANGUAGE"
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- @ref awk_ext "AWK LANGUAGE EXTENSIONS"
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- @ref awk_ext_vardecl " VARIABLE DECLARATION"
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- @ref awk_ext_include "INCLUDE"
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- @ref awk_ext_rwpipe "TWO-WAY PIPE"
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- @ref awk_ext_return "RETURN"
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- @ref awk_ext_comment "COMMENT"
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- @ref awk_ext_fnc "EXTENDED FUNCTIONS"
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- @ref awk_ext_fs "EXTENDED FS"
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- @ref awk_ext_binnum "BINARY NUMBER"
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- @ref awk_ext_unicode "UNICODE ESCAPE SEQUENCE"
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- @ref awk_ext_ioenc "I/O ENCODING"
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- @ref awk_ext_vardecl "VARIABLE DECLARATION"
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- @ref awk_ext_include "INCLUDE"
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- @ref awk_ext_print "EXTENDED PRINT/PRINTF"
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- @ref awk_ext_exprgroup "GROUPED EXPRESSION"
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- @ref awk_ext_rwpipe "TWO-WAY PIPE"
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- @ref awk_ext_return "RETURN"
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- @ref awk_ext_comment "COMMENT"
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- @ref awk_ext_fnc "EXTENDED FUNCTIONS"
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- @ref awk_ext_fs "EXTENDED FS"
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- @ref awk_ext_binnum "BINARY NUMBER"
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- @ref awk_ext_unicode "UNICODE ESCAPE SEQUENCE"
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- @ref awk_ext_ioenc "I/O ENCODING"
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@section awk_intro INTRODUCTION
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@ -289,6 +291,51 @@ blocks appear. To use \@include, you must turn on #QSE_AWK_INCLUDE.
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BEGIN { func_in_abc (); }
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@endcode
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@subsection awk_ext_print EXTENDED PRINT/PRINTF
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When #QSE_AWK_TOLERANT is on, print and printf are treated as if
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they are function calls. In this mode, they return a negative number
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on failure and a zero on success and any I/O failure doesn't abort
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a running program.
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@code
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BEGIN {
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a = print "hello, world" > "/dev/null";
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print a;
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a = print ("hello, world") > "/dev/null";
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print a;
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}
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@endcode
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Since print and printf are like function calls, you can use them
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in any context where a normal expression is allowed. For example,
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printf is used as a conditional expression in an 'if' statement
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in the sample code below.
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@code
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BEGIN {
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if ((printf "hello, world\n" || "tcp://127.0.0.1:9999") <= -1)
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print "FAILURE";
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else
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print "SUCCESS";
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}
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@endcode
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@subsection awk_ext_exprgroup GROUPED EXPRESSION
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When #QSE_AWK_TOLERANT is on, you can use a grouped expression without
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the 'in' operator. A grouped expression is a parentheses-enclosed list
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of expressions separated with a comma. Each expression in the group is
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evaluated in the appearing order. The evaluation result of the last
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expression in the group is returned as that of the group.
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@code
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BEGIN {
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c = (1, 2, 9);
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a=((1*c, 3*c), (3 - c), ((k = 6+(c+1, c+2)), (-7 * c)));
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print c; # 9;
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print a; # -63
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print k; # 17
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}
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@endcode
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@subsection awk_ext_rwpipe TWO-WAY PIPE
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The two-way pipe indicated by @b || is supproted, in addition to the one-way
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@ -352,6 +399,77 @@ BEGIN {
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}
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@endcode
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Here is a more interesting example adopting Michael Sanders'
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AWK web server, modified for QSEAWK.
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@code
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#
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# Michael Sanders' AWK web server for QSEAWK.
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# Orginal code in http://awk.info/?tools/server
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#
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# qseawk --tolerant=on --rwpipe=on webserver.awk
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#
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BEGIN {
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x = 1 # script exits if x < 1
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port = 8080 # port number
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host = "tcpd://0.0.0.0:" port # host string
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url = "http://localhost:" port # server url
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status = 200 # 200 == OK
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reason = "OK" # server response
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RS = ORS = "\r\n" # header line terminators
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doc = Setup() # html document
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len = length(doc) + length(ORS) # length of document
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while (x) {
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if ($1 == "GET") RunApp(substr($2, 2))
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if (! x) break
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print "HTTP/1.0", status, reason || host
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print "Connection: Close" || host
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print "Pragma: no-cache" || host
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print "Content-length:", len || host
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print ORS doc || host
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close(host) # close client connection
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host || getline # wait for new client request
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}
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# server terminated...
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doc = Bye()
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len = length(doc) + length(ORS)
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print "HTTP/1.0", status, reason || host
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print "Connection: Close" || host
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print "Pragma: no-cache" || host
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print "Content-length:", len || host
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print ORS doc || host
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close(host)
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}
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function Setup() {
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tmp = "<html>\
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<head><title>Simple gawk server</title></head>\
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<body>\
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<p><a href=" url "/xterm>xterm</a>\
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<p><a href=" url "/xcalc>xcalc</a>\
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<p><a href=" url "/xload>xload</a>\
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<p><a href=" url "/exit>terminate script</a>\
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</body>\
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</html>"
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return tmp
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}
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function Bye() {
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tmp = "<html>\
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<head><title>Simple gawk server</title></head>\
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<body><p>Script Terminated...</body>\
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</html>"
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return tmp
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}
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function RunApp(app) {
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if (app == "xterm") {system("xterm&"); return}
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if (app == "xcalc" ) {system("xcalc&"); return}
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if (app == "xload" ) {system("xload&"); return}
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if (app == "exit") {x = 0}
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}
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@endcode
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@subsection awk_ext_return RETURN
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The return statement is valid in pattern-action blocks as well as in functions. The execution of a calling block is aborted once the return statement is executed.
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@ -515,4 +633,5 @@ PEER: ?好!
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Note that 你 has been converted to a question mark since the letter is
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not supported by cp949.
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*/
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