Documentation Source Text: Check-in [01a939084b]

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Overview

Comment:	Updates to the matrix generator so that it outputs prototype evidence comments for easy cut-and-paste into test cases. Rewrite the CASE section of the SQL expression documentation.
Timelines:	family \| ancestors \| descendants \| both \| trunk
Files:	files \| file ages \| folders
SHA1:	01a939084b7a1b050185e1fb770c287be06dfa9e
User & Date:	drh 2009-12-12 18:29:41

Context

2009-12-12
23:58		Continuing improvements to the SQL language documentation. check-in: f9931b6e49 user: drh tags: trunk
18:29		Updates to the matrix generator so that it outputs prototype evidence comments for easy cut-and-paste into test cases. Rewrite the CASE section of the SQL expression documentation. check-in: 01a939084b user: drh tags: trunk
15:32		Fix some requirements markings. Changes the evidence scanner to understand that requirement text that begins with "--" is comment, not actual requirement text. check-in: 88da6668cb user: drh tags: trunk

Changes

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Changes to matrix.tcl.

                (reqno, reqtext, origtext, reqimage,srcfile,srcseq)
          VALUES($reqno,$req,    $orig,    1,      $srcfile,$seqno);
      }
    }
  }
}
db eval COMMIT



















########################################################################
# Header output routine adapted from wrap.tcl.  Keep the two in sync.
#
# hd_putsin4 is like puts except that it removes the first 4 indentation
# characters from each line.  It also does variable substitution in
# the namespace of its calling procedure.
................................................................................
    }
    

    </style>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  }
  puts $fd {</head>}





  putsin4 $fd {<body>
    <div><!-- container div to satisfy validator -->
    
    <a href="${path}index.html">
    <img class="logo" src="${path}images/SQLite.gif" alt="SQLite Logo"
     border="0"></a>
    <div><!-- IE hack to prevent disappearing logo--></div>
    <div class="tagline">Small. Fast. Reliable.<br>Choose any three.</div>

    <table width=100% style="clear:both"><tr><td>
      <div class="se"><div class="sw"><div class="ne"><div class="nw">
      <div class="toolbar">
        <a href="${path}about.html">About</a>
        <a href="${path}sitemap.html">Sitemap</a>
        <a href="${path}docs.html">Documentation</a>
................................................................................
        <a href="${path}copyright.html">License</a>
        <a href="${path}news.html">News</a>
        <!-- <a href="${path}dev.html">Developers</a> -->
        <a href="${path}support.html">Support</a>
      </div></div></div></div></div>
    </td></tr></table>
  }
  if {[file exists DRAFT]} {
    putsin4 $fd {
      <p align="center"><font size="6" color="red">*** DRAFT ***</font></p>
    }
  }
}
# End of code copied out of wrap.tcl
##############################################################################

# Generate the requirements traceability matrix.
#
puts "Generating requirements matrix..."
................................................................................
  }
  regsub -all {[^a-zA-Z0-9]} [file tail [file root $srcfile]] _ docid
  puts $out "<td><a href=\"matrix_s$docid.html\">summary</a></td>"
  puts $out "<td><a href=\"matrix_d$docid.html\">details</a></td></tr>\n"
}
puts $out </table>
close $out


















# Detail matrixes for each document.
#
foreach srcfile $srclist {
  regsub -all {[^a-zA-Z0-9]} [file tail [file root $srcfile]] _ docid
  set fn matrix_d$docid.html
  set matrixname($srcfile) $fn
  set out [open doc/matrix/$fn w]
  regsub {^doc/} $srcfile {} basename
  write_header ../ $out "SQLite Requirement Matrix: [file tail $srcfile]"
  puts $out "<h1 align=center>SQLite Requirement Matrix Details<br>"
  puts $out "[file tail $srcfile]</h1>"
  puts $out "<h2><a href=\"matrix.html\">Index</a>"
  puts $out "<a href=\"matrix_s$docid.html\">Summary</a></h2>"
  puts $out {<dl>}


  db eval {
    SELECT reqno, reqimage, origtext
      FROM requirement
     WHERE srcfile=$srcfile
     ORDER BY srcseq
  } {
    puts $out "<dt><a name=\"$reqno\"></a>"
    puts $out "<p><a href=\"$basename#$reqno\">$reqno</a>"

    set ev(tcl) 0
    set ev(th3) 0
    set ev(src) 0
    db eval {
      SELECT count(*) AS cnt, srcclass 
................................................................................
        set cx evok
        incr proof($reqno)
      } else {
        set cx evnil
      }
      puts $out "<cite class=$cx>$srcclass</cite>"
    }
    puts $out "</p></dt>"
    puts $out "<dd><p>$origtext</p>"
    set sep <p>

    db eval {
      SELECT srccat || '/' || srcfile || ':' || srcline AS x, url
        FROM evidence
       WHERE reqno=$reqno
       ORDER BY x;
................................................................................
      if {$url!=""} {
        puts $out "$sep<a href=\"$url\">$x</a>"
      } else {
        puts $out "$sep$x"
      }
      set sep "&nbsp;&nbsp;"
    }











    puts $out "</dd>"
  }
  puts $out {</dl>}


  close $out
}

# Summary matrixes for each document.
#
foreach srcfile $srclist {
  set has_req($srcfile) 1








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                (reqno, reqtext, origtext, reqimage,srcfile,srcseq)
          VALUES($reqno,$req,    $orig,    1,      $srcfile,$seqno);
      }
    }
  }
}
db eval COMMIT
set cnt [db one {SELECT count(*) FROM requirement}]
set evcnt [db one {
  SELECT count(*) FROM requirement WHERE reqno IN (SELECT reqno FROM evidence)
}]
set evpct [format {%.1f%%} [expr {$evcnt*100.0/$cnt}]]
puts "Found $cnt testable statements. Evidence exists for $evcnt or $evpct"

# Report all evidence for which there is no corresponding requirement.
# Such evidence is probably "stale" - the requirement text has changed but
# the evidence text did not.
#
db eval {
  SELECT reqno, srcfile, srcline FROM evidence
   WHERE reqno NOT IN (SELECT reqno FROM requirement)
} {
  puts "ERROR: stale evidence at $srcfile:$srcline - $reqno"
}


########################################################################
# Header output routine adapted from wrap.tcl.  Keep the two in sync.
#
# hd_putsin4 is like puts except that it removes the first 4 indentation
# characters from each line.  It also does variable substitution in
# the namespace of its calling procedure.
................................................................................
    }
    

    </style>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  }
  puts $fd {</head>}
  if {[file exists DRAFT]} {
    set tagline {<font size="6" color="red">*** DRAFT ***</font>}
  } else {
    set tagline {Small. Fast. Reliable.<br>Choose any three.}
  }
  putsin4 $fd {<body>
    <div><!-- container div to satisfy validator -->
    
    <a href="${path}index.html">
    <img class="logo" src="${path}images/SQLite.gif" alt="SQLite Logo"
     border="0"></a>
    <div><!-- IE hack to prevent disappearing logo--></div>
    <div class="tagline">${tagline}</div>

    <table width=100% style="clear:both"><tr><td>
      <div class="se"><div class="sw"><div class="ne"><div class="nw">
      <div class="toolbar">
        <a href="${path}about.html">About</a>
        <a href="${path}sitemap.html">Sitemap</a>
        <a href="${path}docs.html">Documentation</a>
................................................................................
        <a href="${path}copyright.html">License</a>
        <a href="${path}news.html">News</a>
        <!-- <a href="${path}dev.html">Developers</a> -->
        <a href="${path}support.html">Support</a>
      </div></div></div></div></div>
    </td></tr></table>
  }





}
# End of code copied out of wrap.tcl
##############################################################################

# Generate the requirements traceability matrix.
#
puts "Generating requirements matrix..."
................................................................................
  }
  regsub -all {[^a-zA-Z0-9]} [file tail [file root $srcfile]] _ docid
  puts $out "<td><a href=\"matrix_s$docid.html\">summary</a></td>"
  puts $out "<td><a href=\"matrix_d$docid.html\">details</a></td></tr>\n"
}
puts $out </table>
close $out

# Split a long string of text at spaces so that no line exceeds 70
# characters.  Send the result to $out.
#
proc wrap_in_comment {out prefix txt} {
  while {[string length $txt]>70} {
    set break [string last { } $txt 70]
    if {$break == 0} {
      set break [string first { } $txt]
    }
    puts $out "$prefix [string range $txt 0 [expr {$break-1}]]"
    set txt [string trim [string range $txt $break end]]
  }
  puts $out "$prefix $txt"
}



# Detail matrixes for each document.
#
foreach srcfile $srclist {
  regsub -all {[^a-zA-Z0-9]} [file tail [file root $srcfile]] _ docid
  set fn matrix_d$docid.html
  set matrixname($srcfile) $fn
  set out [open doc/matrix/$fn w]
  regsub {^doc/} $srcfile {} basename
  write_header ../ $out "SQLite Requirement Matrix: [file tail $srcfile]"
  puts $out "<h1 align=center>SQLite Requirement Matrix Details<br>"
  puts $out "[file tail $srcfile]</h1>"
  puts $out "<h2><a href=\"matrix.html\">Index</a>"
  puts $out "<a href=\"matrix_s$docid.html\">Summary</a>"
  puts $out "<a href=\"$basename\">Markup</a>"
  puts $out "<a href=\"../$basename\">Original</a></h2>"

  db eval {
    SELECT reqno, reqimage, origtext, reqtext
      FROM requirement
     WHERE srcfile=$srcfile
     ORDER BY srcseq
  } {
    puts $out "<hr><a name=\"$reqno\"></a>"
    puts $out "<p><a href=\"$basename#$reqno\">$reqno</a>"

    set ev(tcl) 0
    set ev(th3) 0
    set ev(src) 0
    db eval {
      SELECT count(*) AS cnt, srcclass 
................................................................................
        set cx evok
        incr proof($reqno)
      } else {
        set cx evnil
      }
      puts $out "<cite class=$cx>$srcclass</cite>"
    }
    puts $out "</p>"
    puts $out "<p>$origtext</p>"
    set sep <p>

    db eval {
      SELECT srccat || '/' || srcfile || ':' || srcline AS x, url
        FROM evidence
       WHERE reqno=$reqno
       ORDER BY x;
................................................................................
      if {$url!=""} {
        puts $out "$sep<a href=\"$url\">$x</a>"
      } else {
        puts $out "$sep$x"
      }
      set sep "&nbsp;&nbsp;"
    }

    # Generate text suitable for copy-paste into source documents as
    # evidence that the requirement is satisfied.
    #
    set abbrev [string range $reqno 0 12]
    puts $out "<pre>/* IMP: $abbrev */</pre>"
    if {[regexp {^syntax diagram } $reqtext]} {
      puts $out "<pre># EVIDENCE-OF: $abbrev -- $reqtext</pre>"
    } else {
      puts $out "<pre>"
      wrap_in_comment $out # "EVIDENCE-OF: $abbrev $reqtext"
      puts $out "</pre>"
    }


  }
  close $out
}

# Summary matrixes for each document.
#
foreach srcfile $srclist {
  set has_req($srcfile) 1

Changes to pages/lang.in.

<p>^(The BETWEEN operator is equivalent to a pair of comparisons.
"<i>a</i> <b>BETWEEN</b> <i>b</i> <b>AND</b> <i>c</i>" is 
equivalent to 
"<i>a</i><b>&gt;=</b><i>b</i> <b>AND</b> <i>a</i><b>&lt;=</b><i>c</i>".)^
^The precedence of the BETWEEN operator is the same as the precedence
as operators <b>==</b> and <b>!=</b> and <b>LIKE</b> and groups left to right.

<tcl>hd_fragment {CASE expression}</tcl>
<h3>The CASE expression</h3>
<p>^(A CASE expression consists of the CASE keyword, an optional expression
(the "base" expression), one or more WHEN...THEN clauses, an optional
ELSE clause, and a closing END keyword.)^
^If the CASE as a base expression, then that expression is evaluated once
and the result is compared to the expression in between the WHEN and THEN
keywords for the WHEN clauses moving from left to right until a match is
found or all WHEN clauses are tested.  ^As soon as a match is found,
the expression that occurs after then THEN keyword becomes the result
of the overall CASE expression.  ^None of the other expressions to the left
of the THEN expression are ever evaluated.  ^If no WHEN terms match the
base expression, then the expression in the ELSE clause is evaluated and becomes
the result of the CASE expression, or the result of the CASE is NULL if
there is no ELSE clause.</p>

<p>^If a CASE expression has no base expression, then the WHEN phrases are
examined from left to write until a WHEN phrase where the expression between
the WHEN and THEN keywords evaluates to true.  ^A NULL value is considered
false for the purposes of this test.  ^When a true WHEN expression is
discovered, the corresponding THEN expression is evaluated and becomes the
result of the overall CASE expression.  ^If no WHEN expression evaluates to
to true, then the ELSE expression becomes the result if the ELSE clause
exists, otherwise the result is NULL.</p>

<p>^The base expression is evaluated exactly once.
^WHEN expressions are evaluated from left to write until a match is
found.  ^WHEN expressions to the right the matching WHEN are never evaluated.
^If any WHEN expression matches, its THEN expression is evaluated and
becomes the result of the overall CASE expression.  ^No THEN expression
is evaluated except the one THEN expression that corresponds to a
matching WHEN.  ^The ELSE expression is only evaluated if no WHEN
expression match.</p>

<p>^If the base expression is NULL then the result of the CASE is the



result of the ELSE expression if it exists, or NULL if the ELSE clause
is omitted.</p>


<h3>Table Column Names</h3>
<p>^A column name can be any of the names defined in the [CREATE TABLE]
statement or one of the following special identifiers: "<b>ROWID</b>",








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<p>^(The BETWEEN operator is equivalent to a pair of comparisons.
"<i>a</i> <b>BETWEEN</b> <i>b</i> <b>AND</b> <i>c</i>" is 
equivalent to 
"<i>a</i><b>&gt;=</b><i>b</i> <b>AND</b> <i>a</i><b>&lt;=</b><i>c</i>".)^
^The precedence of the BETWEEN operator is the same as the precedence
as operators <b>==</b> and <b>!=</b> and <b>LIKE</b> and groups left to right.

<tcl>hd_fragment case {CASE expression}</tcl>
<h3>The CASE expression</h3>
<p>A CASE expression serves a role similar to IF-THEN-ELSE in other
programming languages.  ^WHEN expressions are evaluated from left to
right until one is found that is true and the corresponding THEN term
becomes the result.  ^If no WHEN expression is true then the ELSE 
clause determines the result or the result is NULL if there is no ELSE clase.
</p>

<p>The optional expression that occurs in between the CASE keyword and the
first WHEN keyword is the "base" expression.  ^There are two basic forms
of a CASE expression: those with and without a base expression.
^In a CASE without a base expression, each WHEN expression is evaluted
as a boolean and the overall result is determined by first WHEN expression
that is true.
^In a CASE with a base expression, the base expression is evaluted just
once and the result is compared against each WHEN expression until a 
match is found.
^When comparing a base expression against a WHEN expression, the same
collating sequence, affinity, and NULL-handling rules apply as if the
base expression and WHEN expression are respectively the left- and
right-hand operands of an <big><b>=</b></big> operator.</p>

<p>^(Assuming the subexpressions have no side-effects, the following
two expressions are equivalent:</p>

<ul>
<li>CASE x WHEN w1 THEN r1 WHEN w2 THEN r2 ELSE r3 END
<li>CASE WHEN x=w1 THEN r1 WHEN x=w2 THEN r2 ELSE r3 END
</ul>)^

<p>^The only difference between the two CASE expressions shown above
is that the <i>x</i> expression is evaluated
exactly once in the first example but might be evaluated multiple times
in the second.</p>

<p>^A NULL result is considered false when evaluating WHEN terms.
^If the base expression is NULL then the result of the CASE is the
result of the ELSE expression if it exists, or NULL if the ELSE clause
is omitted.</p>


<h3>Table Column Names</h3>
<p>^A column name can be any of the names defined in the [CREATE TABLE]
statement or one of the following special identifiers: "<b>ROWID</b>",