Caret/js/file.js

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define(["manos"], function(M) {
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/*
Unfortunately, mimicking Node isn't really feasible given the Chrome OS security model, but we still don't want to deal with the annoying Chrome filesystem APIs. This module wraps those in a more usable File object.
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*/
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var noop = function() {};
var File = function(entry) {
this.entry = entry || null;
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this.onWrite = noop;
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};
File.prototype = {
open: function(mode, c) {
var self = this;
if (typeof mode == "function") {
c = mode;
mode = "open";
}
//mode is "open" or "save"
var modes = {
"open": "openWritableFile",
"save": "saveFile"
};
chrome.fileSystem.chooseEntry({
type: modes[mode]
}, function(entry) {
//cancelling acts like an error, but isn't.
if (!entry) return;
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self.entry = entry;
c(null, self)
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});
},
read: function(c) {
if (!this.entry) {
console.error(this);
c("File not opened", null);
}
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var reader = new FileReader();
reader.onload = function() {
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c(null, reader.result);
};
reader.onerror = function() {
console.error("File read error!");
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c(err, null);
};
this.entry.file(function(f) {
reader.readAsText(f);
});
},
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write: function(data, c) {
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var self = this;
if (!this.entry) {
//guard against cases where we accidentally write before opening
self.open("save", function() {
self.write(data, c);
});
return;
}
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c = c || function() {};
M.chain(
//check permissions
function(next) {
chrome.fileSystem.isWritableEntry(self.entry, next);
},
//if read-only, try to open as writable
function(ok, next) {
if (!ok) {
return chrome.fileSystem.getWritableEntry(self.entry, function(entry) {
if (entry) {
self.entry = entry;
next();
} else {
c("Couldn't open file as writable", self);
}
});
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}
next();
},
//write file
function() {
self.entry.createWriter(function(writer) {
writer.onerror = function(err) {
console.error(err);
c(err, self);
}
writer.onwriteend = function() {
//after truncation, actually write the file
writer.onwriteend = function() {
c(null, self);
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self.onWrite();
}
var blob = new Blob([data]);
writer.write(blob);
};
writer.truncate(0);
});
}
);
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},
stat: function(c) {
if (this.entry) {
return this.entry.file(function(f) {
c(null, f);
});
}
return c("No entry");
},
retain: function() {
return chrome.fileSystem.retainEntry(this.entry);
},
restore: function(id, c) {
var self = this;
chrome.fileSystem.isRestorable(id, function(is) {
if (is) {
chrome.fileSystem.restoreEntry(id, function(entry) {
if (!entry) return c("restoreEntry() failed for " + id, null);
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self.entry = entry;
c(null, self);
});
} else {
c("isRestorable() returned false for " + id, null);
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}
});
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},
getPath: function(c) {
chrome.fileSystem.getDisplayPath(this.entry, c);
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}
};
return File;
});