C++: Summary metrics queries

This is a first attempt at implementing, for C++, the set of summary queries that we expect all languages to implement to help diagnose extraction failures and build configuration problems. See the spec in [this document](https://docs.google.com/document/d/1V3zpkj0OGh8GEUVwACRx7fiafE5zklujAftZaYUyf9s/edit?usp=sharing). The five queries are:

- Total number of source files (including .c/.cpp and header files)
- Total number of lines of text across all text files
- Total number of lines of code across all text files
- Number of lines of text in each source file
- Number of lines of code in each source file

I've added some simple unit tests that cover all five of these.

cpp/ql/src/Diagnostics/Files.ql

@@ -0,0 +1,10 @@
+/**
+ * @name Total source files
+ * @description The total number of source files.
+ * @kind metric
+ * @id cpp/metrics/files
+ */
+
+import cpp
+
+select count(File f | f.fromSource())

cpp/ql/src/Diagnostics/Lines.ql

@@ -0,0 +1,10 @@
+/**
+ * @name Total lines of text
+ * @description The total number of lines of text across all source files.
+ * @kind metric
+ * @id cpp/metrics/lines
+ */
+
+import cpp
+
+select sum(File f | f.fromSource() | f.getMetrics().getNumberOfLines())

cpp/ql/src/Diagnostics/LinesOfCode.ql

@@ -0,0 +1,10 @@
+/**
+ * @name Total lines of code
+ * @description The total number of lines of code across all source files.
+ * @kind metric
+ * @id cpp/metrics/lines-of-code
+ */
+
+import cpp
+
+select sum(File f | f.fromSource() | f.getMetrics().getNumberOfLinesOfCode())

cpp/ql/src/Diagnostics/LinesOfCodePerFile.ql

@@ -0,0 +1,12 @@
+/**
+ * @name Lines of code per source file
+ * @description The number of lines of code for each source file.
+ * @kind metric
+ * @id cpp/metrics/lines-of-code-per-file
+ */
+
+import cpp
+
+from File f
+where f.fromSource()
+select f, f.getMetrics().getNumberOfLinesOfCode()

cpp/ql/src/Diagnostics/LinesPerFile.ql

@@ -0,0 +1,12 @@
+/**
+ * @name Lines of text per source file
+ * @description The number of lines of text for each source file.
+ * @kind metric
+ * @id cpp/metrics/lines-per-file
+ */
+
+import cpp
+
+from File f
+where f.fromSource()
+select f, f.getMetrics().getNumberOfLines()

cpp/ql/test/query-tests/Diagnostics/Files.expected

@@ -0,0 +1 @@
+| 3 |

cpp/ql/test/query-tests/Diagnostics/Files.qlref

@@ -0,0 +1 @@
+Diagnostics/Files.ql

cpp/ql/test/query-tests/Diagnostics/Lines.expected

@@ -0,0 +1 @@
+| 122 |

cpp/ql/test/query-tests/Diagnostics/Lines.qlref

@@ -0,0 +1 @@
+Diagnostics/Lines.ql

cpp/ql/test/query-tests/Diagnostics/LinesOfCode.expected

@@ -0,0 +1 @@
+| 93 |

cpp/ql/test/query-tests/Diagnostics/LinesOfCode.qlref

@@ -0,0 +1 @@
+Diagnostics/LinesOfCode.ql

cpp/ql/test/query-tests/Diagnostics/LinesOfCodePerFile.expected

@@ -0,0 +1,3 @@
+| empty-file.cpp:0:0:0:0 | empty-file.cpp | 0 |
+| large-file.cpp:0:0:0:0 | large-file.cpp | 90 |
+| short-file.cpp:0:0:0:0 | short-file.cpp | 3 |

cpp/ql/test/query-tests/Diagnostics/LinesOfCodePerFile.qlref

@@ -0,0 +1 @@
+Diagnostics/LinesOfCodePerFile.ql

cpp/ql/test/query-tests/Diagnostics/LinesPerFile.expected

@@ -0,0 +1,3 @@
+| empty-file.cpp:0:0:0:0 | empty-file.cpp | 0 |
+| large-file.cpp:0:0:0:0 | large-file.cpp | 119 |
+| short-file.cpp:0:0:0:0 | short-file.cpp | 3 |

cpp/ql/test/query-tests/Diagnostics/LinesPerFile.qlref

@@ -0,0 +1 @@
+Diagnostics/LinesPerFile.ql

cpp/ql/test/query-tests/Diagnostics/large-file.cpp

@@ -0,0 +1,119 @@
+int a00(float x) {
+    return (int)x;
+}
+
+int a01(float x) {
+    return (int)x;
+}
+
+int a02(float x) {
+    return (int)x;
+}
+
+int a03(float x) {
+    return (int)x;
+}
+
+int a04(float x) {
+    return (int)x;
+}
+
+int a05(float x) {
+    return (int)x;
+}
+
+int a06(float x) {
+    return (int)x;
+}
+
+int a07(float x) {
+    return (int)x;
+}
+
+int a08(float x) {
+    return (int)x;
+}
+
+int a09(float x) {
+    return (int)x;
+}
+
+int a10(float x) {
+    return (int)x;
+}
+
+int a11(float x) {
+    return (int)x;
+}
+
+int a12(float x) {
+    return (int)x;
+}
+
+int a13(float x) {
+    return (int)x;
+}
+
+int a14(float x) {
+    return (int)x;
+}
+
+int a15(float x) {
+    return (int)x;
+}
+
+int a16(float x) {
+    return (int)x;
+}
+
+int a17(float x) {
+    return (int)x;
+}
+
+int a18(float x) {
+    return (int)x;
+}
+
+int a19(float x) {
+    return (int)x;
+}
+
+int a20(float x) {
+    return (int)x;
+}
+
+int a21(float x) {
+    return (int)x;
+}
+
+int a22(float x) {
+    return (int)x;
+}
+
+int a23(float x) {
+    return (int)x;
+}
+
+int a24(float x) {
+    return (int)x;
+}
+
+int a25(float x) {
+    return (int)x;
+}
+
+int a26(float x) {
+    return (int)x;
+}
+
+int a27(float x) {
+    return (int)x;
+}
+
+int a28(float x) {
+    return (int)x;
+}
+
+int a29(float x) {
+    return (int)x;
+}

cpp/ql/test/query-tests/Diagnostics/short-file.cpp

@@ -0,0 +1,3 @@
+int g(float x) {
+    return (int)x;
+}