From aa2c40934df3fdefbb39338f7eef44e79c3c551e Mon Sep 17 00:00:00 2001
From: dkf <donal.k.fellows@manchester.ac.uk>
Date: Mon, 13 Jan 2014 08:06:43 +0000
Subject: extend [string is] to booleans

---
 generic/tclAssembly.c   |  1 +
 generic/tclCompCmdsSZ.c | 51 +++++++++++++++++++++++++++++++++++++++++++++----
 generic/tclCompile.c    |  3 +++
 generic/tclCompile.h    |  3 ++-
 generic/tclExecute.c    | 11 +++++++++++
 5 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/generic/tclAssembly.c b/generic/tclAssembly.c
index 70379c6..f10bca8 100644
--- a/generic/tclAssembly.c
+++ b/generic/tclAssembly.c
@@ -478,6 +478,7 @@ static const TalInstDesc TalInstructionTable[] = {
     {"tclooIsObject",	ASSEM_1BYTE,	INST_TCLOO_IS_OBJECT,	1,	1},
     {"tclooNamespace",	ASSEM_1BYTE,	INST_TCLOO_NS,		1,	1},
     {"tclooSelf",	ASSEM_1BYTE,	INST_TCLOO_SELF,	0,	1},
+    {"tryCvtToBoolean",	ASSEM_1BYTE,	INST_TRY_CVT_TO_BOOLEAN,1,	2},
     {"tryCvtToNumeric",	ASSEM_1BYTE,	INST_TRY_CVT_TO_NUMERIC,1,	1},
     {"uminus",		ASSEM_1BYTE,	INST_UMINUS,		1,	1},
     {"unset",		ASSEM_BOOL_LVT4,INST_UNSET_SCALAR,	0,	0},
diff --git a/generic/tclCompCmdsSZ.c b/generic/tclCompCmdsSZ.c
index 1436a20..91bb94c 100644
--- a/generic/tclCompCmdsSZ.c
+++ b/generic/tclCompCmdsSZ.c
@@ -514,14 +514,57 @@ TclCompileStringIsCmd(
     case STR_IS_UPPER:
     case STR_IS_WORD:
     case STR_IS_XDIGIT:
-	/* Not yet implemented */
-	return TCL_ERROR;
+	return TclCompileBasicMin0ArgCmd(interp, parsePtr, cmdPtr, envPtr);
 
     case STR_IS_BOOL:
     case STR_IS_FALSE:
     case STR_IS_TRUE:
-	/* Not yet implemented */
-	return TCL_ERROR;
+	CompileWord(envPtr, tokenPtr, interp, parsePtr->numWords-1);
+	OP(		TRY_CVT_TO_BOOLEAN);
+	switch (t) {
+	    int over, over2;
+
+	case STR_IS_BOOL:
+	    if (allowEmpty) {
+		JUMP1(	JUMP_TRUE, over);
+		PUSH(	"");
+		OP(	STR_EQ);
+		JUMP1(	JUMP, over2);
+		FIXJUMP1(over);
+		OP(	POP);
+		PUSH(	"1");
+		FIXJUMP1(over2);
+	    } else {
+		OP4(	REVERSE, 2);
+		OP(	POP);
+	    }
+	    return TCL_OK;
+	case STR_IS_TRUE:
+	    JUMP1(	JUMP_TRUE, over);
+	    if (allowEmpty) {
+		PUSH(	"");
+		OP(	STR_EQ);
+	    } else {
+		OP(	POP);
+		PUSH(	"0");
+	    }
+	    FIXJUMP1(	over);
+	    OP(		LNOT);
+	    OP(		LNOT);
+	    return TCL_OK;
+	case STR_IS_FALSE:
+	    JUMP1(	JUMP_TRUE, over);
+	    if (allowEmpty) {
+		PUSH(	"");
+		OP(	STR_NEQ);
+	    } else {
+		OP(	POP);
+		PUSH(	"1");
+	    }
+	    FIXJUMP1(	over);
+	    OP(		LNOT);
+	    return TCL_OK;
+	}
 
     case STR_IS_DOUBLE: {
 	int satisfied, isEmpty;
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index c01571f..39fa241 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -624,6 +624,9 @@ InstructionDesc const tclInstructionTable[] = {
     {"numericType",	 1,	0,	  0,	{OPERAND_NONE}},
 	/* Pushes the numeric type code of the word at the top of the stack.
 	 * Stack:  ... value => ... typeCode */
+    {"tryCvtToBoolean",	 1,	+1,	  0,	{OPERAND_NONE}},
+	/* Try converting stktop to boolean if possible. No errors.
+	 * Stack:  ... value => ... value isStrictBool */
 
     {NULL, 0, 0, 0, {OPERAND_NONE}}
 };
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index 6bf5daf..a08a93a 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -793,9 +793,10 @@ typedef struct ByteCode {
 #define INST_TCLOO_NEXT			179
 
 #define INST_NUM_TYPE			180
+#define INST_TRY_CVT_TO_BOOLEAN		181
 
 /* The last opcode */
-#define LAST_INST_OPCODE		180
+#define LAST_INST_OPCODE		181
 
 /*
  * Table describing the Tcl bytecode instructions: their name (for displaying
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 2707ec1..989b7b6 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -6461,6 +6461,17 @@ TEBCresume(
      * -----------------------------------------------------------------
      */
 
+    case INST_TRY_CVT_TO_BOOLEAN:
+	valuePtr = OBJ_AT_TOS;
+	if (valuePtr->typePtr == &tclBooleanType) {
+	    objResultPtr = TCONST(1);
+	} else {
+	    int result = (TclSetBooleanFromAny(NULL, valuePtr) == TCL_OK);
+	    objResultPtr = TCONST(result);
+	}
+	TRACE_WITH_OBJ(("\"%.30s\" => ", O2S(valuePtr)), objResultPtr);
+	NEXT_INST_F(1, 0, 1);
+
     case INST_BREAK:
 	/*
 	DECACHE_STACK_INFO();
-- 
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