The internal types of a TclObject js Object (in the C-Implementation a TclObj) are:
Parsing rules for Tcl script input are corresponding to the Dodekalog.
The reason for partially parsing the Tcl input is mostly performance and to some extent later on easier handling of the execution of a statement. Partially parsing is done in the following way: all the tokenizing for Tcl is done, but no variables are expanded, no bracket commands are executed and braced parts are handled as one token. And also within quoted strings the parts, which have later on to be expanded are parsed into separate “word_part” TclObject js Objects. Same is done for array names and array references.
returned from parsing are:
For “normal” Tcl code the tokens from TOKEN_WORD_SEP to TOKEN_COMMENT are returned
Tokens TOKEN_DECIMAL to TOKEN_STR_NI are returned for expression like parts in if, while and in the expr command. The last few ones are used internally for partially parsed statements.
| String | Token | Value |
|---|---|---|
| $abc | TOKEN_VAR | abc |
| ${abc def} | TOKEN_BRACED_VAR | |
| TOKEN_BRACE | ||
| TOKEN_STR | abc | |
| ${abc def} | TOKEN_BRACED_VAR | |
| x(y) | TOKEN_ARRAY_NAME | x0x01y |
| $x(y) | TOKEN_VAR_ARRAY | |
| ${x}(y) | TOKEN_VAR_ARRAY_NAME | |
| set a 1 | TOKEN_CMD | |
| {a y} | TOKEN_BRACE | a y |
| “abc” | TOKEN_QUOTED_STRING | abc |
| “abcx a$y{d e f}yyy” | TOKEN_QUOTED_STRING | |
| TOKEN_STR | abc | |
| TOKEN_CMD | x a | |
| TOKEN_VAR | y | |
| TOKEN_BRACE | d e f | |
| TOKEN_STR | yyy | |
| xyz | TOKEN_STR | xyz |
| {*} | TOKEN_EXPAND | “” |
Some commands use a statement part as en expression to be evaluated and to return a value of true or false like if and while for the condition or the Tcl expr command. For these the condition is parsed to an expression tree existing of nodes (TclNode js Object ). When tokenizing an expression string first all parts are put into nodes objects and these TclNode js Objects are placed in a tree with the operator as the parent node and the operands as the child nodes. A paren “(“ is also a parent node. The nodes are first put in parsing order in the expression tree and afterward the expression tree is reorganized according to the precedence rules o the operators.
are:
| + | TOKEN_PLUS | |
| - | TOKEN_MINUS | |
| * | TOKEN_MUL | |
| / | TOKEN_DIV | |
| % | TOKEN_MOD | |
| < | TOKEN_LT | |
| > | TOKEN_GT | |
| <= | TOKEN_LE | |
| >= | TOKEN_GE | |
| != | TOKEN_NE | |
| == | TOKEN_EQ | |
| ! | TOKEN_NOT | |
| ( | TOKEN_PAREN | pseudo operator used for precedence handling |
| ) | TOKEN_RP | pseudo operator used for precedence handling |
| & | TOKEN_AND | |
| | | TOKEN_OR | |
| ^ | TOKEN_EXOR | |
| && | TOKEN_AND_IF | |
| || | TOKEN_OR_IF | |
| eq | TOKEN_STR_EQ | |
| ne | TOKEN_STR_NE | |
| in | TOKEN_STR_IN | |
| ni | TOKEN_STR_NI |
are (as in C):
| TOKEN_OR_IF | 1 |
| TOKEN_AND_IF | 2 |
| TOKEN_OR | 3 |
| TOKEN_EXOR | 4 |
| TOKEN_AND | 5 |
| TOKEN_EQ | 6 |
| TOKEN_NE | 6 |
| TOKEN_LT | 7 |
| TOKEN_GT | 7 |
| TOKEN_LE | 7 |
| TOKEN_GE | 7 |
| TOKEN_PLUS | 9 |
| TOKEN_MINUS | 9 |
| TOKEN_MUL | 10 |
| TOKEN_DIV | 10 |
| TOKEN_MOD | 10 |
| TOKEN_PAREN | 12 |
| TOKEN_STR | 99 |
Reorganizing is done in flipping nodes that have a higher precedence:
Some tokens are used only internal during parsing:
| TOKEN_EOL | the separator for a Tcl statement either “\r”, “\n” or a “;” |
| TOKEN_WORD_SEP | space or tab between words |
| TOKEN_ESC | for signaling the different parts of a word like in yyya bccc |
| one part is yyy one part is the TOKEN_CMD “a b” and one | |
| part is ccc. In between TOKEN_ESC is returned to signal | |
| these parts | |
| TOKEN_EOF | at the end of the code to parse |
Some tokens are only used within expression trees:
| TOKEN_INTEGER | 1 to n digits 0-9 |
| TOKEN_DECIMAL | an integer with a leading unary “+” or “-” |
| TOKEN_REAL | a decimal with a “.” as the fraction separator, a fraction and an |
| exponent with e+/-nnn syntax | |
| TOKEN_BOOLEAN | the Tcl values for a boolean, true/false/0/1 … |
| TOKEN_HEX | 0x followed by 0-9A-Fa-f characters |
| TOKEN_OCTAL | 0-7 1 to n characters |
(Part of itcl in Javascript Paper)