TIP 429 Implementation: [string cat]

6 files changed, 180 insertions, 7 deletions

diff --git a/doc/string.n b/doc/string.n
index 72a69ff..9108e7c 100644
--- a/doc/string.n
+++ b/doc/string.n
@@ -19,6 +19,14 @@ string \- Manipulate strings
 Performs one of several string operations, depending on \fIoption\fR.
 The legal \fIoption\fRs (which may be abbreviated) are:
 .TP
+\fBstring cat\fR ?\fIstring1\fR? ?\fIstring2...\fR?
+.
+Concatenate the given strings just like direct juxtaposition
+would. This primitive is occasionally handier than juxtaposition when
+mixed quoting is wanted, or when the aim is to return the result of a
+concatenation without resorting to \fB[return -level 0]\fR. If no arg
+is present, an empty string is returned.
+.TP
 \fBstring compare\fR ?\fB\-nocase\fR? ?\fB\-length\fI length\fR? \fIstring1 string2\fR
 .
 Perform a character-by-character comparison of strings \fIstring1\fR
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index 0f7f20a..ea5d7a4 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -2838,6 +2838,76 @@ StringCmpCmd(
 /*
  *----------------------------------------------------------------------
  *
+ * StringCatCmd --
+ *
+ *	This procedure is invoked to process the "string cat" Tcl command.
+ *	See the user documentation for details on what it does.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	See the user documentation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+StringCatCmd(
+    ClientData dummy,		/* Not used. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    int tot, i, length;
+    char *bytes, *p;
+    Tcl_Obj *objResultPtr;
+
+    /*
+     * NOTE: this implementation aims for simplicity, not speed, because all
+     * speed-critical uses of [string cat] will involve the compiled variant
+     * anyway. Thus we avoid code duplication (from TEBC/INST_CONCAT1) without
+     * sacrificing perf.
+     */
+	
+    if (objc < 2) {
+	/*
+	 * If there are no args, the result is an empty object.
+	 * Just leave the preset empty interp result.
+	 */
+	return TCL_OK;
+    }
+    tot = 0;
+    for(i = 1;i < objc;i++) {
+	bytes = TclGetStringFromObj(objv[i], &length);
+	if (bytes != NULL) {
+	    tot += length;
+	}
+    }
+    if (tot < 0) {
+	/* TODO: convert panic to error ? */
+	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
+    }
+    p = ckalloc(tot + 1);
+    TclNewObj(objResultPtr);
+    objResultPtr->bytes = p;
+    objResultPtr->length = tot;
+    for (i = 1;i < objc;i++) {
+	bytes = TclGetStringFromObj(objv[i], &length);
+	if (bytes != NULL) {
+	    memcpy(p, bytes, (size_t) length);
+	    p += length;
+	}
+    }
+    *p = '\0';
+    Tcl_SetObjResult(interp,objResultPtr);
+    
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * StringBytesCmd --
  *
  *	This procedure is invoked to process the "string bytelength" Tcl
@@ -3330,6 +3400,7 @@ TclInitStringCmd(
 {
     static const EnsembleImplMap stringImplMap[] = {
 	{"bytelength",	StringBytesCmd,	TclCompileBasic1ArgCmd, NULL, NULL, 0},
+	{"cat",		StringCatCmd,	TclCompileStringCatCmd, NULL, NULL, 0},
 	{"compare",	StringCmpCmd,	TclCompileStringCmpCmd, NULL, NULL, 0},
 	{"equal",	StringEqualCmd,	TclCompileStringEqualCmd, NULL, NULL, 0},
 	{"first",	StringFirstCmd,	TclCompileStringFirstCmd, NULL, NULL, 0},
diff --git a/generic/tclCompCmdsSZ.c b/generic/tclCompCmdsSZ.c
index e6ec0a6..8ade6a5 100644
--- a/generic/tclCompCmdsSZ.c
+++ b/generic/tclCompCmdsSZ.c
@@ -269,6 +269,39 @@ TclCompileSetCmd(
  */
 
 int
+TclCompileStringCatCmd(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    int numWords = parsePtr->numWords;
+    Tcl_Token *wordTokenPtr = TokenAfter(parsePtr->tokenPtr);
+    DefineLineInformation;	/* TIP #280 */
+
+    if (numWords>=2) {
+	int i;
+
+	for (i = 1; i < numWords; i++) {
+	    CompileWord(envPtr, wordTokenPtr, interp, i);
+	    wordTokenPtr = TokenAfter(wordTokenPtr);
+	}
+	while (numWords > 256) {
+	    TclEmitInstInt1(INST_STR_CONCAT1, 255, envPtr);
+	    numWords -= 254;	/* concat pushes 1 obj, the result */
+	}
+	if (numWords > 2) {
+	    TclEmitInstInt1(INST_STR_CONCAT1, numWords - 1, envPtr);
+	}
+    } else {
+	PushStringLiteral(envPtr, "");
+    }
+    return TCL_OK;
+}
+
+int
 TclCompileStringCmpCmd(
     Tcl_Interp *interp,		/* Used for error reporting. */
     Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 1bb2103..6bf1ef9 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -3646,6 +3646,9 @@ MODULE_SCOPE int	TclCompileReturnCmd(Tcl_Interp *interp,
 MODULE_SCOPE int	TclCompileSetCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
+MODULE_SCOPE int	TclCompileStringCatCmd(Tcl_Interp *interp,
+			    Tcl_Parse *parsePtr, Command *cmdPtr,
+			    struct CompileEnv *envPtr);
 MODULE_SCOPE int	TclCompileStringCmpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
diff --git a/tests/string.test b/tests/string.test
index a8a83d9..54d02e8 100644
--- a/tests/string.test
+++ b/tests/string.test
@@ -30,7 +30,7 @@ testConstraint memory [llength [info commands memory]]
 
 test string-1.1 {error conditions} {
     list [catch {string gorp a b} msg] $msg
-} {1 {unknown or ambiguous subcommand "gorp": must be bytelength, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
+} {1 {unknown or ambiguous subcommand "gorp": must be bytelength, cat, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
 test string-1.2 {error conditions} {
     list [catch {string} msg] $msg
 } {1 {wrong # args: should be "string subcommand ?arg ...?"}}
@@ -54,7 +54,7 @@ test string-2.6 {string compare} {
     string compare abcde abdef
 } -1
 test string-2.7 {string compare, shortest method name} {
-    string c abcde ABCDE
+    string co abcde ABCDE
 } 1
 test string-2.8 {string compare} {
     string compare abcde abcde
@@ -81,7 +81,7 @@ test string-2.13 {string compare -nocase} {
     string compare -nocase abcde abdef
 } -1
 test string-2.14 {string compare -nocase} {
-    string c -nocase abcde ABCDE
+    string compare -nocase abcde ABCDE
 } 0
 test string-2.15 {string compare -nocase} {
     string compare -nocase abcde abcde
@@ -1513,7 +1513,7 @@ test string-20.1 {string trimright errors} {
 } {1 {wrong # args: should be "string trimright string ?chars?"}}
 test string-20.2 {string trimright errors} {
     list [catch {string trimg a} msg] $msg
-} {1 {unknown or ambiguous subcommand "trimg": must be bytelength, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
+} {1 {unknown or ambiguous subcommand "trimg": must be bytelength, cat, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
 test string-20.3 {string trimright} {
     string trimright "    XYZ      "
 } {    XYZ}
@@ -1572,7 +1572,7 @@ test string-21.14 {string wordend, unicode} {
 
 test string-22.1 {string wordstart} {
     list [catch {string word a} msg] $msg
-} {1 {unknown or ambiguous subcommand "word": must be bytelength, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
+} {1 {unknown or ambiguous subcommand "word": must be bytelength, cat, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
 test string-22.2 {string wordstart} {
     list [catch {string wordstart a} msg] $msg
 } {1 {wrong # args: should be "string wordstart string index"}}
@@ -1969,6 +1969,30 @@ test string-28.13 {tcl::prefix longest} {
     tcl::prefix longest {ax\x90 bep ax\x91} a
 } ax
 
+test string-29.1 {string cat, no arg} {
+    string cat
+} ""
+test string-29.2 {string cat, single arg} {
+    set x [pid]
+    string compare $x [string cat $x]
+} 0
+test string-29.3 {string cat, two args} {
+    set x [pid]
+    string compare $x$x [string cat $x $x]
+} 0
+test string-29.4 {string cat, many args} {
+    set x [pid]
+    set n 260
+    set xx [string repeat $x $n]
+    set vv [string repeat {$x} $n]
+    set vvs [string repeat {$x } $n]
+    set r1 [string compare $xx [subst $vv]]
+    set r2 [string compare $xx [eval "string cat $vvs"]]
+    list $r1 $r2
+} {0 0}
+
+
+
 # cleanup
 rename MemStress {}
 catch {rename foo {}}
diff --git a/tests/stringComp.test b/tests/stringComp.test
index 165ef20..083399b 100644
--- a/tests/stringComp.test
+++ b/tests/stringComp.test
@@ -46,7 +46,7 @@ if {[testConstraint memory]} {
 test stringComp-1.1 {error conditions} {
     proc foo {} {string gorp a b}
     list [catch {foo} msg] $msg
-} {1 {unknown or ambiguous subcommand "gorp": must be bytelength, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
+} {1 {unknown or ambiguous subcommand "gorp": must be bytelength, cat, compare, equal, first, index, is, last, length, map, match, range, repeat, replace, reverse, tolower, totitle, toupper, trim, trimleft, trimright, wordend, or wordstart}}
 test stringComp-1.2 {error conditions} {
     proc foo {} {string}
     list [catch {foo} msg] $msg
@@ -210,7 +210,7 @@ foreach {tname tbody tresult tcode} {
 
 # need a few extra tests short abbr cmd
 test stringComp-3.1 {string compare, shortest method name} {
-    proc foo {} {string c abcde ABCDE}
+    proc foo {} {string co abcde ABCDE}
     foo
 } 1
 test stringComp-3.2 {string equal, shortest method name} {
@@ -735,6 +735,40 @@ test stringComp-14.2 {Bug 82e7f67325} memory {
 
 ## string word*
 ## not yet bc
+
+## string cat
+test stringComp-29.1 {string cat, no arg} {
+    proc foo {} {string cat}
+    foo
+} ""
+test stringComp-29.2 {string cat, single arg} {
+    proc foo {} {
+	set x [pid]
+	string compare $x [string cat $x]
+    }
+    foo
+} 0
+test stringComp-29.3 {string cat, two args} {
+    proc foo {} {
+	set x [pid]
+	string compare $x$x [string cat $x $x]
+    }
+    foo
+} 0
+test stringComp-29.4 {string cat, many args} {
+    proc foo {} {
+	set x [pid]
+	set n 260
+	set xx [string repeat $x $n]
+	set vv [string repeat {$x} $n]
+	set vvs [string repeat {$x } $n]
+	set r1 [string compare $xx [subst $vv]]
+	set r2 [string compare $xx [eval "string cat $vvs"]]
+	list $r1 $r2
+    }
+    foo
+} {0 0}
+
 
 # cleanup
 catch {rename foo {}}