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index.js
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index.js
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var parseSchema = require('protocol-buffers-schema');
var primitive = require('./types');
var fs = require('fs');
var path = require('path');
function Compiler(filename) {
this.messages = {};
this.enums = {};
this.schema = this.open(filename);
}
Compiler.prototype.open = function(filename) {
if (!/\.proto$/i.test(filename) && !fs.existsSync(filename)) {
filename += '.proto';
}
var schema = parseSchema(fs.readFileSync(filename, 'utf-8'));
this.visit(schema, schema.package || '');
schema.imports.forEach(function(i) {
this.open(path.resolve(path.dirname(filename), i));
}, this);
return schema;
};
/**
* Visits a schema in the tree, and assigns messages and enums to the lookup tables.
*/
Compiler.prototype.visit = function(schema, prefix) {
if (schema.enums) {
schema.enums.forEach(function(e) {
e.id = prefix + (prefix ? '.' : '') + (e.id || e.name);
this.enums[e.id] = e;
this.visit(e, e.id);
}, this);
}
if (schema.messages) {
schema.messages.forEach(function(m) {
m.id = prefix + (prefix ? '.' : '') + (m.id || m.name);
this.messages[m.id] = m;
this.visit(m, m.id);
}, this);
}
};
/**
* Top level compile method. If a type name is provided,
* compiles just that type and its dependencies. Otherwise,
* compiles all types in the file.
*/
Compiler.prototype.compile = function(opts, type) {
this.root = {
definitions: {},
used: {}
};
if (type) {
this.resolve(opts, type, '');
} else {
this.schema.messages.forEach(function(message) {
this.resolve(opts, message.id, '');
}, this);
this.schema.enums.forEach(function(e) {
this.resolve(opts, e.id, '');
}, this);
}
delete this.root.used;
return this.root;
};
/**
* Resolves a type name at the given path in the schema tree.
* Returns a compiled JSON schema.
*/
Compiler.prototype.resolve = function(opts, type, from, base, key) {
if (primitive[type])
return primitive[type];
var lookup = from.split('.');
for (var i = lookup.length; i >= 0; i--) {
var id = lookup.slice(0, i).concat(type).join('.');
// If this type was used before, move it from inline to a reusable definition
if (this.root.used[id] && !this.root.definitions[id]) {
var k = this.root.used[id];
this.root.definitions[id] = k[0][k[1]];
k[0][k[1]] = { $ref: '#/definitions/' + id };
}
// If already defined, reuse
if (this.root.definitions[id])
return { $ref: '#/definitions/' + id };
// Compile the message or enum
var res;
if (this.messages[id])
res = this.compileMessage(opts, this.messages[id]);
if (this.enums[id])
res = this.compileEnum(this.enums[id]);
if (res) {
// If used, or at the root level, make a definition
if (this.root.used[id] || !base) {
this.root.definitions[id] = res;
res = { $ref: '#/definitions/' + id };
}
// Mark as used if not an Enum
if (base && !this.root.used[id] && !this.enums[id])
this.root.used[id] = [base, key];
return res;
}
}
throw new Error('Could not resolve ' + type);
};
/**
* Compiles and assigns a type
*/
Compiler.prototype.build = function(opts, type, from, base, key) {
var res = this.resolve(opts, type, from, base, key);
if (base)
base[key] = res;
};
/**
* Compiles a protobuf enum to JSON schema
*/
Compiler.prototype.compileEnum = function(enumType, root) {
var res = {
title: enumType.name,
type: 'string',
enum: Object.keys(enumType.values)
};
return res;
};
/**
* Compiles a protobuf message to JSON schema
*/
Compiler.prototype.compileMessage = function(opts, message, root) {
var res = {
title: message.name,
type: 'object',
properties: {},
additionalProperties: opts.allow_additional_props,
required: []
};
message.fields.forEach(function(field) {
if (field.map) {
if (field.map.from !== 'string')
throw new Error('Can only use strings as map keys at ' + message.id + '.' + field.name);
var f = res.properties[field.name] = {
type: 'object',
additionalProperties: null
};
this.build(opts, field.map.to, message.id, f, 'additionalProperties');
} else {
if (field.repeated) {
var f = res.properties[field.name] = {
type: 'array',
items: null
};
this.build(opts, field.type, message.id, f, 'items');
} else {
this.build(opts, field.type, message.id, res.properties, field.name);
}
}
if (field.required)
res.required.push(field.name);
}, this);
if (res.required.length === 0)
delete res.required;
return res;
};
module.exports = function(opts, filename, model) {
var compiler = new Compiler(filename);
return compiler.compile(opts, model);
};