feature: add api for enumeration lookups

index.js

@@ -16,6 +16,8 @@
  * limitations under the License.
  */
 
+const pgns = require('./lib/pgns')
+
 module.exports = {
   FromPgn: require('./lib/fromPgn').Parser,
   parseN2kString: require('./lib/stringMsg').parseN2kString,
@@ -37,7 +39,9 @@ module.exports = {
   VenusMQTT: require('./lib/venus-mqtt'),
   discover: require('./lib/discovery'),
   SimpleCan: require('./lib/simpleCan'),
-  addCustomPgn: require('./lib/pgns').addCustomPgn
+  addCustomPgn: pgns.addCustomPgn,
+  lookupEnumerationValue: pgns.lookupEnumerationValue,
+  lookupEnumerationName: pgns.lookupEnumerationName
 }
 
 try {

lib/fromPgn.js

@@ -19,7 +19,7 @@ const trace = require('debug')('canboatjs:fromPgn:trace')
 const EventEmitter = require('events')
 const pkg = require('../package.json')
 const _ = require('lodash')
-const { pgns, getCustomPgn, addCustomPgn } = require('./pgns')
+const { pgns, getCustomPgn, addCustomPgn, lookupEnumNameForField } = require('./pgns')
 const BitStream = require('bit-buffer').BitStream
 const BitView = require('bit-buffer').BitView
 const Int64LE = require('int64-buffer').Int64LE
@@ -543,15 +543,8 @@ function pad(n, p, c)
 }
 
 function lookup(field, value) {
-  if (!field.value2name) {
-    field.value2name = {};
-    field.EnumValues.forEach(function(enumPair) {
-      field.value2name[Number(enumPair.value)] = enumPair.name
-    })
-  }
-  var name = field.value2name[value]
+  var name = lookupEnumNameForField(field, value)
   return name ? name : value
-  //return name
 }
 
 function lookupBitField(field, value) {

lib/pgns.js

@@ -35,14 +35,83 @@ function organizePGNs() {
   return res
 }
 
+/** doing this for now, when we move to the new canboat.json, we'll get from there*/
+const enumMappings = {
+  SHIP_TYPE: {
+    pgn: 129040,
+    field: 'Type of ship'
+  }
+}
+
+function getField(pgn, name) {
+  return pgn.Fields.find(f => f.Name === name)
+}
+
+function lookupEnumerationName(enumName, value) {
+  let mapping = enumMappings[enumName]
+  if ( mapping ) {
+    let pgn = getPgn0(mapping.pgn)
+    if ( pgn ) {
+      let field = getField(pgn, mapping.field)
+      return field && lookupEnumNameForField(field, value)
+    }
+  }
+}
+
+function lookupEnumerationValue(enumName, name) {
+  let mapping = enumMappings[enumName]
+  if ( mapping ) {
+    let pgn = getPgn0(mapping.pgn)
+    if ( pgn ) {
+      let field = getField(pgn, mapping.field)
+      return field && lookupEnumValueForField(field, name)
+    }
+  }
+}
+
+function getValue2Name(field) {
+  if (!field.value2name && field.EnumValues) {
+    field.value2name = {};
+    field.EnumValues.forEach(function(enumPair) {
+      field.value2name[Number(enumPair.value)] = enumPair.name
+    })
+  }
+  return field.value2name
+}
+
+function getName2Value(field) {
+  if (!field.name2value && field.EnumValues) {
+    field.name2value = {};
+    field.EnumValues.forEach(function(enumPair) {
+      field.name2value[enumPair.name] = Number(enumPair.value)
+    })
+  }
+  return field.name2value
+}
+
+function lookupEnumNameForField(field, value) {
+  let value2name = getValue2Name(field)
+  return value2name && value2name[value]
+}
+
+function lookupEnumValueForField(field, stringValue) {
+  let name2value = getName2Value(field)
+  return name2value && name2value[stringValue]
+}
+
 const organizedPGNs = organizePGNs()
 const getPgn = pgn => organizedPGNs[pgn]
+const getPgn0 = flow(getPgn, first)
 const customPgns = {}
 
 module.exports = {
   getPgn,
-  getPgn0: flow(getPgn, first),
+  getPgn0,
   pgns: organizedPGNs,
+  lookupEnumValueForField,
+  lookupEnumNameForField,
+  lookupEnumerationName,
+  lookupEnumerationValue,
   addCustomPgn: (pgn) => {
     if ( !customPgns[pgn.PGN] ) {
       customPgns[pgn.PGN] = {
@@ -62,5 +131,7 @@ module.exports = {
   },
   getCustomPgn: (pgnNum) => {
     return customPgns[pgnNum]
+  },
+  getEnumForField: (pgnNumber, fieldName) => {
   }
 }

lib/toPgn.js

@@ -15,7 +15,7 @@
  */
 
 const { getField } = require('./fromPgn')
-const { pgns, getCustomPgn } = require('./pgns')
+const { pgns, getCustomPgn, lookupEnumValueForField } = require('./pgns')
 const _ = require('lodash')
 const BitStream = require('bit-buffer').BitStream
 const Int64LE = require('int64-buffer').Int64LE
@@ -270,13 +270,7 @@ function writeVariableLengthField(bs, pgn_number, pgn, field, value) {
 }
 
 function lookup(field, stringValue) {
-  if (!field.name2value) {
-    field.name2value = {};
-    field.EnumValues.forEach(function(enumPair) {
-      field.name2value[enumPair.name] = Number(enumPair.value)
-    })
-  }
-  var res = field.name2value[stringValue];
+  var res = lookupEnumValueForField(field, stringValue)
   return _.isUndefined(res) ? stringValue : res
 }
 

test/enum_lookups.js

@@ -0,0 +1,21 @@
+const chai = require('chai')
+chai.Should()
+chai.use(require('chai-things'))
+chai.use(require('chai-json-equal'));
+
+const { lookupEnumerationValue, lookupEnumerationName} = require('../index')
+
+describe('enumeration lookups work', function () {
+  it(`name lookup works`, function (done) {
+    chai.expect(lookupEnumerationName('SHIP_TYPE', 21))
+      .eq('Wing In Ground (hazard cat X)')
+    done()
+  })
+
+  it(`value lookup works`, function (done) {
+    chai.expect(lookupEnumerationValue('SHIP_TYPE',
+                                       'Wing In Ground (hazard cat X)'))
+      .eq(21)
+    done()
+  })
+})