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| -rw-r--r-- | txr.1 | 57 |
1 files changed, 42 insertions, 15 deletions
@@ -41808,24 +41808,51 @@ object, using the dot notation unnecessarily. The non-overlapping semantics of .code sme -develops as follows. When the +evolves as follows. In the following description, it is understood +that a match is required at every step. If that match fails, then +the entire +.code sme +operator fails: + +.RS +.IP 1. +First, .meta spat -pattern matches a prefix of the input object, then a middle suffix is -calculated of the input object by dropping leading elements from it. The number -of elements dropped is equal to the length +is required to match a a prefix of the input list. If the match +succeeds, then a +.I "middle suffix" +of the input is calculated by dropping from it leading +elements. The number of elements dropped is equal to the length of .metn spat . -The -.meta mpat -is then similarly matched against a prefix of this middle suffix. If that match -is successful, a number of leading elements equal to the length of -.meta mpat -is dropped from the middle suffix to determine the final suffix. -Then +.IP 2. +The middle suffix is then searched for an occurrence of the middle pattern +.metn mpat , +as if using the +.code scan +pattern operator. All elements skipped by the search are dropped, +until a match is found. +.IP 3. +At that point, if +.meta mvar +has been specified, it is bound to the remaining input, which still +includes the part which just matched +.metn mpat . +.IP 4. +Next, a number of elements equal to the length of +.metn mpat , +are dropped from the middle suffix, leaving a residue comprising the +.IR "final suffix" . +.IP 5. +The end pattern .meta epat -is matched against the tail portion of the final suffix which is equal -to its length. If the final suffix is shorter than -.metn epat , -then the match isn't possible. +must then match a suffix of the final suffix. +.IP 6. +If the +.meta evar +variable has been specified, it is bound to the entire suffix that +was matched by +.metn epat . +.RE .TP* Examples: |