diff options
| -rw-r--r-- | generic/tclCompile.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/generic/tclCompile.c b/generic/tclCompile.c index 6f5ef50..05daabf 100644 --- a/generic/tclCompile.c +++ b/generic/tclCompile.c @@ -1764,6 +1764,7 @@ CompileCommandTokens( assert (numWords > 0); + /* Determine whether any words of the command require expansion */ for (wordIdx = 0; wordIdx < numWords; wordIdx++, tokenPtr += tokenPtr->numComponents + 1) { if (tokenPtr->type == TCL_TOKEN_EXPAND_WORD) { @@ -1772,6 +1773,7 @@ CompileCommandTokens( } } + /* Do we know the command word? */ Tcl_IncrRefCount(cmdObj); tokenPtr = parsePtr->tokenPtr; cmdKnown = TclWordKnownAtCompileTime(tokenPtr, cmdObj); @@ -1791,6 +1793,7 @@ CompileCommandTokens( } } } + /* If cmdPtr != NULL, we will try to call cmdPtr->compileProc */ /* Pre-Compile */ @@ -2112,7 +2115,22 @@ TclCompileScript( p = next; if (parse.numWords == 0) { - /* TODO: Document justification */ + /* + * The "command" parsed has no words. In this case + * we can skip the rest of the loop body. With no words, + * clearly CompileCommandTokens() has nothing to do. Since + * the parser aggressively sucks up leading comment and white + * space, including newlines, parse.commandStart must be + * pointing at either the end of script, or a command-terminating + * semi-colon. In either case, the TclAdvance*() calls have + * nothing to do. Finally, when no words are parsed, no + * tokens have been allocated at parse.tokenPtr so there's + * also nothing for Tcl_FreeParse() to do. + * + * The advantage of this shortcut is that CompileCommandTokens() + * can be written with an assumption that parse.numWords > 0, + * with the implication the CCT() always generates bytecode. + */ continue; } @@ -2145,7 +2163,7 @@ TclCompileScript( * command is thrown away before moving on to the next command). * For the last command compiled, we need to undo that INST_POP * so that the result of the last command becomes the result of - * the script. These code here removes that trailing INST_POP. + * the script. The code here removes that trailing INST_POP. */ envPtr->cmdMapPtr[lastCmdIdx].numCodeBytes--; envPtr->codeNext--; |