string -- String manipulation

Syntax: string subcommand ?args...?

Subcommand Description
string cat Concatenates zero or more strings
string compare Compares two strings lexicographically
string equal Compares two strings for equality
string first Finds first occurrence of a string
string last Finds last occurrence of a string
string length String length in characters
string map Maps keys to values in a string
string range Extracts a substring
string tolower Converts a string to lower case
string toupper Converts a string to upper case
string trim Trims leading and trailing whitespace
string trimleft Trims leading whitespace
string trimright Trims trailing whitespace

TCL Liens
  • Supports a subset of the subcommands provided by the standard TCL string command. The subset will increase over time.
  • Does not currently support index syntax, e.g., end-1, for the string first, string last, and string range commands. These commands accept simple numeric indices only.

Molt Strings and Unicode

Molt strings are exactly and identically Rust String values, and are treated at the TCL level as vectors of Rust char values. A Rust char is a "Unicode scalar value", and is also (in most cases) a Unicode code point. It is not a not a grapheme; graphemes that consist of multiple code points will be treated as multiple characters. This is more or less the same as Standard TCL, but Unicode being what it is there may be edge cases where behavior will differ slightly.

string cat

Syntax: string cat ?args ...?

Returns the concatenation of zero or more strings.

string compare

Syntax: string compare ?options? string1 string2

Compares the two strings lexicographically, returning -1 if string1 is less than string2, 0 if they are equal, and 1 if string1 is greater than string2.

The options are as follows:

Option Description
-nocase The comparison is case-insensitive.
-length length Only the first length characters will be compared.

Notes:

  • When -nocase is given, the strings are compared by converting them to lowercase using a naive method that may fail for more complex Unicode graphemes.

string equal

Syntax: string equal ?options? string1 string2

Compares the two strings, returning 1 if they are equal, and 0 otherwise.

The options are as follows:

Option Description
-nocase The comparison is case-insensitive.
-length length Only the first length characters will be compared.

Notes:

  • When -nocase is given, the strings are compared by converting them to lowercase using a naive method that may fail for more complex Unicode graphemes.

string first

Syntax: string first needleString haystackString ?startIndex?

Returns the index of the first occurrence of the needleString in the haystackString, or -1 if the needleString is not found. If the startIndex is given, the search will begin at the startIndex.

string last

Syntax: string last needleString haystackString ?startIndex?

Returns the index of the last occurrence of the needleString in the haystackString, or -1 if the needleString is not found. If the startIndex is given, the search will begin at the startIndex.

string length

Syntax: string length string

Returns the length of the string in Rust characters.

string map

Syntax: string map ?-nocase? mapping string

Replaces old substrings in string with new ones based on the key/value pairs in mapping, which is a dictionary or flat key/value list. If -nocase is given, substring matches will be case-insensitive. The command iterates through the string in a single pass, checking for each key in order, so that earlier key replacements have no effect on later key replacements.

string range

Syntax: string range string first last

Returns the substring of string starting with the character whose index is first and ending with the character whose index is last. Values of first that are less than 0 are treated as 0, and values of last that are greater than the index of the last character in the string are treated as that index.

string tolower

Syntax: string tolower string

Converts the string to all lower case, using the standard Rust String::to_lowercase method.

TCL Liens: Tcl 8.6 provides for optional first and last indices; only the text in that range is affected.

string toupper

Syntax: string toupper string

Converts the string to all upper case, using the standard Rust String::to_uppercase method.

TCL Liens: Tcl 8.6 provides for optional first and last indices; only the text in that range is affected.

string trim

Syntax: string trim string

Returns string trimmed of leading and trailing whitespace by the standard Rust String::trim method.

string trimleft

Syntax: string trimleft string

Returns string trimmed of leading whitespace by the standard Rust String::trim_start method.

string trimright

Syntax: string trimright string

Returns string trimmed of trailing whitespace by the standard Rust String::trim_end method.