| 1 | ..reader.. <- TRUE |
| 2 | |
| 3 | if(!exists("..types..")) source("types.r") |
| 4 | |
| 5 | new.Reader <- function(tokens) { |
| 6 | e <- structure(new.env(), class="Reader") |
| 7 | e$tokens <- tokens |
| 8 | e$position <- 1 |
| 9 | e |
| 10 | } |
| 11 | |
| 12 | Reader.peek <- function(rdr) { |
| 13 | if (rdr$position > length(rdr$tokens)) return(NULL) |
| 14 | rdr$tokens[[rdr$position]] |
| 15 | } |
| 16 | |
| 17 | Reader.next <- function(rdr) { |
| 18 | if (rdr$position > length(rdr$tokens)) return(NULL) |
| 19 | rdr$position <- rdr$position + 1 |
| 20 | rdr$tokens[[rdr$position-1]] |
| 21 | } |
| 22 | |
| 23 | tokenize <- function(str) { |
| 24 | re <- "[\\s,]*(~@|[\\[\\]\\{\\}\\(\\)'`~^@]|\"(?:\\\\.|[^\\\\\"])*\"|;.*|[^\\s\\[\\]\\{\\}\\('\"`,;\\)]*)" |
| 25 | m <- lapply(regmatches(str, gregexpr(re, str, perl=TRUE)), |
| 26 | function(e) sub("^[\\s,]+", "", e, perl=TRUE)) |
| 27 | res <- list() |
| 28 | i <- 1 |
| 29 | for(v in m[[1]]) { |
| 30 | if (v == "") next |
| 31 | res[[i]] <- v |
| 32 | i <- i+1 |
| 33 | } |
| 34 | res |
| 35 | } |
| 36 | |
| 37 | re_match <- function(re, str) { length(grep(re, c(str))) > 0 } |
| 38 | |
| 39 | read_atom <- function(rdr) { |
| 40 | token <- Reader.next(rdr) |
| 41 | if (re_match("^-?[0-9][0-9.]*$", token)) { |
| 42 | as.numeric(token) |
| 43 | } else if (substr(token,1,1) == "\"") { |
| 44 | gsub("\\\\n", "\\n", |
| 45 | gsub("\\\\\"", "\"", |
| 46 | substr(token, 2, nchar(token)-1))) |
| 47 | } else if (token == "nil") { |
| 48 | nil |
| 49 | } else if (token == "true") { |
| 50 | TRUE |
| 51 | } else if (token == "false") { |
| 52 | FALSE |
| 53 | } else { |
| 54 | as.symbol(token) |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | read_seq <- function(rdr, start="(", end=")") { |
| 59 | lst <- list() |
| 60 | token <- Reader.next(rdr) |
| 61 | if (token != start) { |
| 62 | throw(concat("expected '", start, "'")) |
| 63 | } |
| 64 | repeat { |
| 65 | token <- Reader.peek(rdr) |
| 66 | if (is.null(token)) { |
| 67 | throw(concat("expected '", end, "', got EOF")) |
| 68 | } |
| 69 | if (token == end) break |
| 70 | lst[[length(lst)+1]] <- read_form(rdr) |
| 71 | } |
| 72 | Reader.next(rdr) |
| 73 | new.listl(lst) |
| 74 | } |
| 75 | |
| 76 | read_form <- function(rdr) { |
| 77 | token <- Reader.peek(rdr) |
| 78 | if (token == ")") { |
| 79 | throw("unexpected ')'") |
| 80 | } else if (token == "(") { |
| 81 | new.listl(read_seq(rdr)) |
| 82 | } else if (token == "]") { |
| 83 | throw("unexpected ']'") |
| 84 | } else if (token == "[") { |
| 85 | new.vectorl(read_seq(rdr, "[", "]")) |
| 86 | } else { |
| 87 | read_atom(rdr) |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | read_str <- function(str) { |
| 92 | tokens <- tokenize(str) |
| 93 | if (length(tokens) == 0) return(nil) |
| 94 | return(read_form(new.Reader(tokens))) |
| 95 | } |
| 96 | |
| 97 | #cat("---\n") |
| 98 | #print(tokenize("123")) |
| 99 | #cat("---\n") |
| 100 | #print(tokenize(" ( 123 456 abc \"def\" ) ")) |
| 101 | |
| 102 | #rdr <- new.reader(tokenize(" ( 123 456 abc \"def\" ) ")) |
| 103 | #Reader.peek(rdr) |
| 104 | #Reader.next(rdr) |
| 105 | #Reader.next(rdr) |
| 106 | #Reader.next(rdr) |
| 107 | #Reader.next(rdr) |
| 108 | #Reader.next(rdr) |
| 109 | #Reader.next(rdr) |
| 110 | #Reader.next(rdr) |