Decoded: OpenTTD (2003) v1.8 (2018)
Source file: smallmap_type.hpp
Line-by-line code walkthrough by MaiZure

smallmap_type.hpp defines SmallMap and SmallPair containers

Original code:
https://github.com/MaiZure/OpenTTD-1.8/blob/master/src/core/smallmap_type.hpp





1     COMMENT (*)
2     BLANK (-)
3     *
4     *
5     *
6     *
7     *
8     *
9     -
10    *
11    -
12    Header guard
13    Header guard
14    -
15    Includes the OpenTTD SmallVector container
16    Includes OpenTTD sort functions
17    -
18    *
19    *
20    *
21    *
22    *
23    Sets up a class template with two parameters: input types
24    BLOCK START - SmallPair, a type-safe container with specific pairs
25    Declares the first pair storage
26    Declares the second pair storage
27    -
28    *
29    Defines a parameterized constructor with initialization list of the state
      to store
30    BLOCK END - SmallPair
31    -
32    *
33    *
34    *
35    *
36    *
37    *
38    *
39    *
40    *
41    Sets up a class template with three parameters: two types and a size with
      default of 16
42    BLOCK START - SmallMap, extends SmallVector and provides operations to
      function as a SmallVector of key/value Pairs
43    Defines a typedef for Pair using this specific type for ease of use
44    Defines a typedef of Pair to use as an interator
45    Defines a similar typedef for a constant interator
46    -
47    *
48    Defines an empty default constructor
49    *
50    Defines an empty destructor
51    -
52    *
53    *
54    *
55    *
56    *
57    Defines Pair with one argument: an input reference to a key string
58    BLOCK START - Find, returns the key or failure
59    Loop through all items in the Vector
60    Test for matching keys, then return the value
61    Loop until all keys are checked
62    If we reach here, look failed. Return end of vector as failure
63    BLOCK END - Find
64    -
65    *
66    *
67    *
68    *
69    *
70    Defines a Pair with a key argument, this time with a non-const return
71    BLOCK START - Find
72    Loop through all items in the Vector
73    Test for matching keys, then return the value
74    Loop until all keys are checked
75    If we reach here, look failed. Return end of vector as failure
76    BLOCK END - Find
77    -
78    *
79    *
80    *
81    *
82    *
83    Defines Contains with one argument: a key
84    BLOCK START - Contains
85    Returns true if Find returns a valid value
86    BLOCK END - Contains
87    -
88    *
89    *
90    *
91    *
92    *
93    Defines Erase with one argument: a key/value pair within the map
94    BLOCK START - Erase
95    Checks that the pointer could lie within the map endpoints
96    Clobbers the pointer in the map
97    BLOCK END - Erase
98    -
99    *
100   *
101   *
102   *
103   *
104   *
105   Defines Erase with one argument, a key reference to lookup
106   BLOCK START - SmallMap::Erase
107   Loop through all pairs in the map
108   If the key matches...
109   Clobber the pair
110   Return true that the erase was successful
111   End check for matching key
112   Repeat loop for all pairs
113   Didn't find the pair, return false for failure to erase
114   BLOCK END - SmallMap::Erase
115   -
116   *
117   *
118   *
119   *
120   *
121   *
122   Defines Insert with two arguments, the key and value for the new pair
123   BLOCK START - SmallMap::Insert
124   If the map already contains a value for the key, return failure
125   Create a new empty pair using the Vector Append interface
126   Set the key
127   Set the value
128   Return true for success
129   BLOCK END - SmallMap::Insert
130   -
131   *
132   *
133   *
134   *
135   *
136   *
137   Defines an overloaded array accessor for the SmallMap with an input key
138   BLOCK START - overloaded [] accessor for input keys
139   Loop through all pairs in the map
140   If the key match a pair in the map then return the value
141   Loop through all pairs
142   If we're here, then it doesn't exist so create a new empty Pair
143   Set the key
144   Return the new key value (default)
145   BLOCK END - overloaded [] accessor
146   -
147   Defines SmallMap::SortByKey with no arguments
148   BLOCK START - SmallMap::SortByKey, calls QSort on map keys
149   Calls Qsort on the map with a length and a function to use
150   BLOCK END - SmallMap::SortByKey
151   -
152   Defines KeySorter, the basic comparator function for the sorter
153   BLOCK START - SmallMap::KeySorter
154   Returns the difference between the key (pointers or hamming distance?)
155   BLOCK END - SmallMap::KeySorter
156   BLOCK END - SmallMap
157   -
158   Header guard end