stdlib: add json.

src/lib/json.rs

@@ -0,0 +1,257 @@
+// Rust JSON serialization library
+// Copyright (c) 2011 Google Inc.
+
+import float;
+import map;
+import option;
+import option::{some, none};
+import str;
+import vec;
+
+export json;
+export to_str;
+export from_str;
+
+export num;
+export string;
+export boolean;
+export list;
+export dict;
+
+/*
+Tag: json
+
+Represents a json value.
+*/
+tag json {
+    /* Variant: num */
+    num(float);
+    /* Variant: string */
+    string(str);
+    /* Variant: boolean */
+    boolean(bool);
+    /* Variant: list */
+    list(@[json]);
+    /* Variant: dict */
+    dict(map::hashmap<str,json>);
+}
+
+/*
+Function: to_str
+
+Serializes a json value into a string.
+*/
+fn to_str(j: json) -> str {
+    alt j {
+        num(f) { float::to_str(f, 6u) }
+        string(s) { #fmt["\"%s\"", s] } // XXX: escape
+        boolean(true) { "true" }
+        boolean(false) { "false" }
+        list(@js) {
+            str::concat(["[",
+                    str::connect(
+                        vec::map::<json,str>({ |e| to_str(e) }, js),
+                        ", "),
+                    "]"])
+        }
+        dict(m) {
+            let parts = [];
+            m.items({ |k, v|
+                        vec::grow(parts, 1u,
+                                  str::concat(["\"", k, "\": ", to_str(v)])
+                        )
+            });
+            str::concat(["{ ", str::connect(parts, ", "), " }"])
+        }
+    }
+}
+
+fn rest(s: str) -> str {
+    assert(str::char_len(s) >= 1u);
+    str::char_slice(s, 1u, str::char_len(s))
+}
+
+fn from_str_str(s: str) -> (option::t<json>, str) {
+    let pos = 0u;
+    let len = str::byte_len(s);
+    let escape = false;
+    let res = "";
+
+    alt str::char_at(s, 0u) {
+        '"' { pos = 1u; }
+        _ { ret (none, s); }
+    }
+
+    while (pos < len) {
+        let chr = str::char_range_at(s, pos);
+        let c = chr.ch;
+        pos = chr.next;
+        if (escape) {
+            res = res + str::from_char(c);
+            escape = false;
+            cont;
+        }
+        if (c == '\\') {
+            escape = true;
+            cont;
+        } else if (c == '"') {
+            ret (some(string(res)), str::char_slice(s, pos, str::char_len(s)));
+        }
+        res = res + str::from_char(c);
+    }
+
+    ret (none, s);
+}
+
+fn from_str_list(s: str) -> (option::t<json>, str) {
+    if str::char_at(s, 0u) != '[' { ret (none, s); }
+    let s0 = str::trim_left(rest(s));
+    let vals = [];
+    if str::is_empty(s0) { ret (none, s0); }
+    if str::char_at(s0, 0u) == ']' { ret (some(list(@[])), rest(s0)); }
+    while str::is_not_empty(s0) {
+        s0 = str::trim_left(s0);
+        let (next, s1) = from_str_helper(s0);
+        s0 = s1;
+        alt next {
+            some(j) { vec::grow(vals, 1u, j); }
+            none { ret (none, s0); }
+        }
+        s0 = str::trim_left(s0);
+        if str::is_empty(s0) { ret (none, s0); }
+        alt str::char_at(s0, 0u) {
+            ',' { }
+            ']' { ret (some(list(@vals)), rest(s0)); }
+            _ { ret (none, s0); }
+        }
+        s0 = rest(s0);
+    }
+    ret (none, s0);
+}
+
+fn from_str_dict(s: str) -> (option::t<json>, str) {
+    if str::char_at(s, 0u) != '{' { ret (none, s); }
+    let s0 = str::trim_left(rest(s));
+    let vals = map::new_str_hash::<json>();
+    if str::is_empty(s0) { ret (none, s0); }
+    if str::char_at(s0, 0u) == '}' { ret (some(dict(vals)), rest(s0)); }
+    while str::is_not_empty(s0) {
+        s0 = str::trim_left(s0);
+        let (next, s1) = from_str_helper(s0);    // key
+        let key = "";
+        s0 = s1;
+        alt next {
+            some(string(k)) { key = k; }
+            _ { ret (none, s0); }
+        }
+        s0 = str::trim_left(s0);
+        if str::is_empty(s0) { ret (none, s0); }
+        if str::char_at(s0, 0u) != ':' { ret (none, s0); }
+        s0 = str::trim_left(rest(s0));
+        let (next, s1) = from_str_helper(s0);    // value
+        s0 = s1;
+        alt next {
+            some(j) { vals.insert(key, j); }
+            _ { ret (none, s0); }
+        }
+        s0 = str::trim_left(s0);
+        if str::is_empty(s0) { ret (none, s0); }
+        alt str::char_at(s0, 0u) {
+            ',' { }
+            '}' { ret (some(dict(vals)), rest(s0)); }
+            _ { ret (none, s0); }
+        }
+        s0 = str::trim_left(rest(s0));
+    }
+    (none, s)
+}
+
+fn from_str_float(s: str) -> (option::t<json>, str) {
+    let pos = 0u;
+    let len = str::byte_len(s);
+    let res = 0f;
+    let neg = 1.f;
+
+    alt str::char_at(s, 0u) {
+        '-' {
+            neg = -1.f;
+            pos = 1u;
+        }
+        '+' {
+            pos = 1u;
+        }
+        '0' to '9' | '.' { }
+        _ { ret (none, s); }
+    }
+
+    while (pos < len) {
+        let opos = pos;
+        let chr = str::char_range_at(s, pos);
+        let c = chr.ch;
+        pos = chr.next;
+        alt c {
+            '0' to '9' {
+                res = res * 10f;
+                res += ((c as int) - ('0' as int)) as float;
+            }
+            '.' { break; }
+            _ { ret (some(num(neg * res)),
+                     str::char_slice(s, opos, str::char_len(s))); }
+        }
+    }
+
+    if pos == len {
+        ret (some(num(neg * res)), str::char_slice(s, pos, str::char_len(s)));
+    }
+
+    let dec = 1.f;
+    while (pos < len) {
+        let opos = pos;
+        let chr = str::char_range_at(s, pos);
+        let c = chr.ch;
+        pos = chr.next;
+        alt c {
+            '0' to '9' {
+                dec /= 10.f;
+                res += (((c as int) - ('0' as int)) as float) * dec;
+            }
+            _ { ret (some(num(neg * res)),
+                     str::char_slice(s, opos, str::char_len(s))); }
+        }
+    }
+    ret (some(num(neg * res)), str::char_slice(s, pos, str::char_len(s)));
+}
+
+fn from_str_bool(s: str) -> (option::t<json>, str) {
+    if (str::starts_with(s, "true")) {
+        (some(boolean(true)), str::slice(s, 4u, str::byte_len(s)))
+    } else if (str::starts_with(s, "false")) {
+        (some(boolean(false)), str::slice(s, 5u, str::byte_len(s)))
+    } else {
+        (none, s)
+    }
+}
+
+fn from_str_helper(s: str) -> (option::t<json>, str) {
+    let s = str::trim_left(s);
+    if str::is_empty(s) { ret (none, s); }
+    let start = str::char_at(s, 0u);
+    alt start {
+        '"' { from_str_str(s) }
+        '[' { from_str_list(s) }
+        '{' { from_str_dict(s) }
+        '0' to '9' | '-' | '+' | '.' { from_str_float(s) }
+        't' | 'f' { from_str_bool(s) }
+        _ { ret (none, s); }
+    }
+}
+
+/*
+Function: from_str
+
+Deserializes a json value from a string.
+*/
+fn from_str(s: str) -> option::t<json> {
+    let (j, _) = from_str_helper(s);
+    j
+}

src/lib/std.rc

@@ -12,7 +12,7 @@ export aio, comm, fs, io, net, run, sio, sys, task;
 export ctypes, either, option, result, util;
 export bitv, deque, fun_treemap, list, map, smallintmap, sort, treemap, ufind;
 export rope;
-export ebml, dbg, getopts, math, rand, sha1, term, time, unsafe;
+export ebml, dbg, getopts, json, math, rand, sha1, term, time, unsafe;
 export extfmt, test;
 // FIXME: generic_os and os_fs shouldn't be exported
 export generic_os, os, os_fs;
@@ -74,6 +74,7 @@ mod ufind;
 mod ebml;
 mod dbg;
 mod getopts;
+mod json;
 mod math;
 mod rand;
 mod sha1;

src/test/stdtest/json.rs

@@ -0,0 +1,48 @@
+use std;
+import std::json::*;
+import std::option::{none, some};
+
+#[test]
+fn test_from_str_num() {
+    assert(from_str("3") == some(num(3f)));
+    assert(from_str("3.1") == some(num(3.1f)));
+    assert(from_str("-1.2") == some(num(-1.2f)));
+    assert(from_str(".4") == some(num(0.4f)));
+}
+
+#[test]
+fn test_from_str_str() {
+    assert(from_str("\"foo\"") == some(string("foo")));
+    assert(from_str("\"\\\"\"") == some(string("\"")));
+    assert(from_str("\"lol") == none);
+}
+
+#[test]
+fn test_from_str_bool() {
+    assert(from_str("true") == some(boolean(true)));
+    assert(from_str("false") == some(boolean(false)));
+    assert(from_str("truz") == none);
+}
+
+#[test]
+fn test_from_str_list() {
+    assert(from_str("[]") == some(list(@[])));
+    assert(from_str("[true]") == some(list(@[boolean(true)])));
+    assert(from_str("[3, 1]") == some(list(@[num(3f), num(1f)])));
+    assert(from_str("[2, [4, 1]]") ==
+        some(list(@[num(2f), list(@[num(4f), num(1f)])])));
+    assert(from_str("[2, ]") == none);
+    assert(from_str("[5, ") == none);
+    assert(from_str("[6 7]") == none);
+    assert(from_str("[3") == none);
+}
+
+#[test]
+fn test_from_str_dict() {
+    assert(from_str("{}") != none);
+    assert(from_str("{\"a\": 3}") != none);
+    assert(from_str("{\"a\": }") == none);
+    assert(from_str("{\"a\" }") == none);
+    assert(from_str("{\"a\"") == none);
+    assert(from_str("{") == none);
+}

src/test/stdtest/stdtest.rc

@@ -6,14 +6,15 @@ mod char;
 mod comm;
 mod deque;
 mod either;
+mod float;
 mod fs;
 mod getopts;
 mod int;
 mod io;
-mod vec;
+mod json;
 mod list;
 mod map;
-mod treemap;
+mod math;
 mod net;
 mod option;
 mod os;
@@ -22,18 +23,18 @@ mod ptr;
 mod qsort3;
 mod qsort;
 mod rand;
+mod result;
+mod rope;
 mod run;
 mod sha1;
 mod sort;
 mod str;
 mod sys;
 mod task;
 mod test;
+mod treemap;
 mod uint;
-mod float;
-mod math;
-mod result;
-mod rope;
+mod vec;
 
 // Local Variables:
 // mode: rust