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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 64 |
1 files changed, 64 insertions, 0 deletions
@@ -41041,6 +41041,70 @@ operator. -> ((2 4) (b d)) .brev +.coNP Pattern operator @ scan +.synb +.mets @(scan << pattern ) +.syne +.desc +The +.code scan +operator matches +.meta pattern +against the corresponding object. If the match fails, and the object +is a +.code cons +cell, the match is tried on the +.code cdr +of the cons cell. The +.code cdr +traversal repeats until a successful match is found, +or a match failure occurs against against an atom. + +Thus, a list object, possibly improper, matches +.meta pattern +under +.code scan +if any suffix of that object matches. + +.TP* Examples: + +.verb + ;; mismatch: 1 doesn't match 2 + (when-match @(scan 2) 1 t) -> t + + ;; simple atom match: 42 matches 42 + (when-match @(scan 42) 42 t) -> t + + ;; (2 3) is a sublist of (1 2 3 4) + (when-match @(scan (2 3 . @nil)) '(1 2 3 4) t) -> t + + ;; (2 @x 4 . @nil) matches (2 3 4), binding x to 3: + (when-match @(scan (2 @x 4 . @nil)) '(1 2 3 4 5) x) -> 3 + + ;; The entire matching suffix can be captured. + (when-match @(scan @(as sfx (2 @x 4 . @nil))) + '(1 2 3 4 5) + sfx) + -> (2 3 4 5) + + ;; Missing . @nil in pattern anchors search to end: + (when-match @(scan (@x 2)) + '(1 2 3 2 4 2) + x) + + ;; Terminating atom anchors to improper end: + (when-match @(scan (@x . 4)) + '(1 2 3 . 4) + x) + -> 3 + + ;; Atom pattern matches only terminating atom + (when-match @(scan #(@x @y)) + '(1 2 3 . #(4 5)) + (list x y)) + -> (4 5) +.brev + .coNP Pattern operators @ and and @ or .synb .mets @(and << pattern *) |