| 1 | Configure Internals
|
|---|
| 2 | ===================
|
|---|
| 3 |
|
|---|
| 4 | [ note: this file uses markdown for formatting ]
|
|---|
| 5 |
|
|---|
| 6 | Intro
|
|---|
| 7 | -----
|
|---|
| 8 |
|
|---|
| 9 | This is a collection of notes that are hopefully of interest to those
|
|---|
| 10 | who decide to dive into Configure and what it does. This is a living
|
|---|
| 11 | document and anyone is encouraged to add to it and submit changes.
|
|---|
| 12 | There's no claim for this document to be complete at any time, but it
|
|---|
| 13 | will hopefully reach such a point in time.
|
|---|
| 14 |
|
|---|
| 15 |
|
|---|
| 16 | ----------------------------------------------------------------------
|
|---|
| 17 |
|
|---|
| 18 | Parsing build.info files, processing conditions
|
|---|
| 19 | -----------------------------------------------
|
|---|
| 20 |
|
|---|
| 21 | Processing conditions in build.info files is done with the help of a
|
|---|
| 22 | condition stack that tell if a build.info should be processed or if it
|
|---|
| 23 | should just be skipped over. The possible states of the stack top are
|
|---|
| 24 | expressed in the following comment from Configure:
|
|---|
| 25 |
|
|---|
| 26 | # The top item of this stack has the following values
|
|---|
| 27 | # -2 positive already run and we found ELSE (following ELSIF should fail)
|
|---|
| 28 | # -1 positive already run (skip until ENDIF)
|
|---|
| 29 | # 0 negatives so far (if we're at a condition, check it)
|
|---|
| 30 | # 1 last was positive (don't skip lines until next ELSE, ELSIF or ENDIF)
|
|---|
| 31 | # 2 positive ELSE (following ELSIF should fail)
|
|---|
| 32 |
|
|---|
| 33 | Ground rule is that non-condition lines are skipped over if the
|
|---|
| 34 | stack top is > 0. Condition lines (IF, ELSIF, ELSE and ENDIF
|
|---|
| 35 | statements) need to be processed either way to keep track of the skip
|
|---|
| 36 | stack states, so they are a little more intricate.
|
|---|
| 37 |
|
|---|
| 38 | Instead of trying to describe in words, here are some example of what
|
|---|
| 39 | the skip stack should look like after each line is processed:
|
|---|
| 40 |
|
|---|
| 41 | Example 1:
|
|---|
| 42 |
|
|---|
| 43 | | IF[1] | 1 | |
|
|---|
| 44 | | ... whatever ... | | this line is processed |
|
|---|
| 45 | | IF[1] | 1 1 | |
|
|---|
| 46 | | ... whatever ... | | this line is processed |
|
|---|
| 47 | | ELSIF[1] | 1 -1 | |
|
|---|
| 48 | | ... whatever ... | | this line is skipped over |
|
|---|
| 49 | | ELSE | 1 -2 | |
|
|---|
| 50 | | ... whatever ... | | this line is skipped over |
|
|---|
| 51 | | ENDIF | 1 | |
|
|---|
| 52 | | ... whatever ... | | this line is processed |
|
|---|
| 53 | | ELSIF[1] | -1 | |
|
|---|
| 54 | | ... whatever ... | | this line is skipped over |
|
|---|
| 55 | | IF[1] | -1 -1 | |
|
|---|
| 56 | | ... whatever ... | | this line is skipped over |
|
|---|
| 57 | | ELSIF[1] | -1 -1 | |
|
|---|
| 58 | | ... whatever ... | | this line is skipped over |
|
|---|
| 59 | | ELSE | -1 -2 | |
|
|---|
| 60 | | ... whatever ... | | this line is skipped over |
|
|---|
| 61 | | ENDIF | -1 | |
|
|---|
| 62 | | ... whatever ... | | this line is skipped over |
|
|---|
| 63 | | ENDIF | | |
|
|---|
| 64 |
|
|---|
| 65 | Example 2:
|
|---|
| 66 |
|
|---|
| 67 | | IF[0] | 0 | |
|
|---|
| 68 | | ... whatever ... | | this line is skipped over |
|
|---|
| 69 | | IF[1] | 0 -1 | |
|
|---|
| 70 | | ... whatever ... | | this line is skipped over |
|
|---|
| 71 | | ELSIF[1] | 0 -1 | |
|
|---|
| 72 | | ... whatever ... | | this line is skipped over |
|
|---|
| 73 | | ELSE | 0 -2 | |
|
|---|
| 74 | | ... whatever ... | | this line is skipped over |
|
|---|
| 75 | | ENDIF | 0 | |
|
|---|
| 76 | | ... whatever ... | | this line is skipped over |
|
|---|
| 77 | | ELSIF[1] | 1 | |
|
|---|
| 78 | | ... whatever ... | | this line is processed |
|
|---|
| 79 | | IF[1] | 1 1 | |
|
|---|
| 80 | | ... whatever ... | | this line is processed |
|
|---|
| 81 | | ELSIF[1] | 1 -1 | |
|
|---|
| 82 | | ... whatever ... | | this line is skipped over |
|
|---|
| 83 | | ELSE | 1 -2 | |
|
|---|
| 84 | | ... whatever ... | | this line is skipped over |
|
|---|
| 85 | | ENDIF | 1 | |
|
|---|
| 86 | | ... whatever ... | | this line is processed |
|
|---|
| 87 | | ENDIF | | |
|
|---|
| 88 |
|
|---|
| 89 | Example 3:
|
|---|
| 90 |
|
|---|
| 91 | | IF[0] | 0 | |
|
|---|
| 92 | | ... whatever ... | | this line is skipped over |
|
|---|
| 93 | | IF[0] | 0 -1 | |
|
|---|
| 94 | | ... whatever ... | | this line is skipped over |
|
|---|
| 95 | | ELSIF[1] | 0 -1 | |
|
|---|
| 96 | | ... whatever ... | | this line is skipped over |
|
|---|
| 97 | | ELSE | 0 -2 | |
|
|---|
| 98 | | ... whatever ... | | this line is skipped over |
|
|---|
| 99 | | ENDIF | 0 | |
|
|---|
| 100 | | ... whatever ... | | this line is skipped over |
|
|---|
| 101 | | ELSIF[1] | 1 | |
|
|---|
| 102 | | ... whatever ... | | this line is processed |
|
|---|
| 103 | | IF[0] | 1 0 | |
|
|---|
| 104 | | ... whatever ... | | this line is skipped over |
|
|---|
| 105 | | ELSIF[1] | 1 1 | |
|
|---|
| 106 | | ... whatever ... | | this line is processed |
|
|---|
| 107 | | ELSE | 1 -2 | |
|
|---|
| 108 | | ... whatever ... | | this line is skipped over |
|
|---|
| 109 | | ENDIF | 1 | |
|
|---|
| 110 | | ... whatever ... | | this line is processed |
|
|---|
| 111 | | ENDIF | | |
|
|---|
| 112 |
|
|---|
| 113 | Example 4:
|
|---|
| 114 |
|
|---|
| 115 | | IF[0] | 0 | |
|
|---|
| 116 | | ... whatever ... | | this line is skipped over |
|
|---|
| 117 | | IF[0] | 0 -1 | |
|
|---|
| 118 | | ... whatever ... | | this line is skipped over |
|
|---|
| 119 | | ELSIF[0] | 0 -1 | |
|
|---|
| 120 | | ... whatever ... | | this line is skipped over |
|
|---|
| 121 | | ELSE | 0 -2 | |
|
|---|
| 122 | | ... whatever ... | | this line is skipped over |
|
|---|
| 123 | | ENDIF | 0 | |
|
|---|
| 124 | | ... whatever ... | | this line is skipped over |
|
|---|
| 125 | | ELSIF[1] | 1 | |
|
|---|
| 126 | | ... whatever ... | | this line is processed |
|
|---|
| 127 | | IF[0] | 1 0 | |
|
|---|
| 128 | | ... whatever ... | | this line is skipped over |
|
|---|
| 129 | | ELSIF[0] | 1 0 | |
|
|---|
| 130 | | ... whatever ... | | this line is skipped over |
|
|---|
| 131 | | ELSE | 1 2 | |
|
|---|
| 132 | | ... whatever ... | | this line is processed |
|
|---|
| 133 | | ENDIF | 1 | |
|
|---|
| 134 | | ... whatever ... | | this line is processed |
|
|---|
| 135 | | ENDIF | | |
|
|---|
| 136 |
|
|---|
